Section 2 · Factors Affecting the Style, Quality and Price of Wine

The Growing Environment

Climate, weather, and soil are the natural forces that shape how grapes ripen and, ultimately, how wine tastes. This chapter covers everything from broad climate categories to the micro-details of a vineyard’s aspect and drainage. If the vine (Chapter 4) is the instrument, the growing environment is the concert hall, it determines what kind of music is possible.

Climate vs Weather

Before diving in, it’s important to understand the difference between these two terms, which the exam expects you to use precisely:

When we say "Burgundy has a cool continental climate," we mean that’s the long-term pattern. But in a specific year, Burgundy might experience unusually warm conditions (producing riper, fuller wines) or a devastating late frost (destroying part of the crop).

Climate Types

Climate Comparison: Temperature & Wine Style

Average growing season temp Cool Moderate Warm Hot High acid Light body Low alcohol Balanced Med body Complex Ripe fruit Full body Higher alc Very ripe High alc Low acid Champagne, Mosel Bordeaux, Burgundy Barossa, S. Rhône Central Valley

The WSET classifies wine-growing climates into four broad categories based on average growing season temperatures. Understanding these categories is fundamental, they tell you what kind of wine a region is likely to produce.

Cool Climate

Average growing season temperatures are at the lower end of what allows grapes to ripen. Grapes ripen slowly, often reaching only moderate sugar levels while retaining high acidity. Wines tend to be lighter-bodied, lower in alcohol, higher in acidity, and display more delicate, floral, or green-fruit aromas.

Examples: Champagne, Mosel (Germany), southern England, Tasmania, Marlborough (marginal cool to moderate)

Typical varieties: Pinot Noir, Chardonnay, Riesling, early-to-mid-ripening varieties that don’t need extreme heat

Risks: Incomplete ripening in poor years, high disease pressure from damp conditions, spring frost

Moderate Climate

Reliable ripening of a wide range of grape varieties. Wines show a balance between fruit ripeness and fresh acidity, neither too lean nor too heavy. Many of the world’s most celebrated wine regions fall into this category.

Examples: Bordeaux, Burgundy (warmer years), northern Rhône, Napa Valley (can be moderate to warm depending on sub-region), Margaret River

Typical varieties: Cabernet Sauvignon, Merlot, Pinot Noir (in the warmer moderate zones), Sauvignon Blanc, Sémillon

Warm Climate

Grapes ripen reliably every year with good sugar levels. Wines tend to be fuller-bodied, higher in alcohol, lower in acidity, and show riper fruit flavours (think dark berries, stone fruit, tropical fruit). Vintage variation is less dramatic than in cool or moderate climates.

Examples: Barossa Valley, McLaren Vale, Mendoza (Argentina), southern Rhône, most of southern Spain

Typical varieties: Shiraz, Grenache, Tempranillo, Mourvèdre, varieties that thrive in heat

Risks: Overripeness (excessively high sugar/alcohol, loss of acidity), sunburn on grapes, drought stress

Hot Climate

Very high temperatures. Without irrigation, viticulture may not be possible. Grapes ripen rapidly and can become overripe quickly. Wines are typically full-bodied, high in alcohol, and may lack freshness and complexity unless careful techniques are used (e.g., picking early, night harvesting, altitude).

Examples: Central Valley (California), inland Australia, parts of north-western China, La Mancha (Spain)

Risks: Excessive heat can shut down vine metabolism entirely (above ~35°C, photosynthesis slows dramatically; above ~40°C, it can stop). Berries can shrivel and raisin on the vine.

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Exam Angle

When a question asks you to describe the climate of a region, always state the category (cool/moderate/warm/hot) and the climate type (maritime/continental/Mediterranean). Then connect that to the style of wine: "Bordeaux has a moderate maritime climate, which provides a long growing season with enough warmth to ripen Cabernet Sauvignon while maintaining freshness through maritime-influenced acidity."

What Shapes Climate: Continental, Maritime, and Mediterranean

Beyond the temperature-based categories above, climates are also described by the influence that shapes them. This matters because it affects not just average temperatures but also temperature variation, rainfall patterns, and seasonal risks.

Continental Climate

Found inland, away from the moderating influence of large bodies of water. Continental climates have large temperature differences between summer and winter (hot summers, very cold winters) and between day and night (warm days, cool nights). Rainfall tends to occur in spring and summer.

Wine effect: Hot summers ripen grapes well, but cold winters can damage vines. Large day-night temperature swings during ripening help preserve acidity while allowing sugar to accumulate, this produces wines with good balance.

Examples: Burgundy (continental, though some maritime influence), Alsace, Austria, parts of Washington State, Mendoza (Argentina)

Risks: Severe winter cold, spring frost, summer hail

Maritime Climate

Found near oceans or large bodies of water. Water heats up and cools down more slowly than land, so maritime climates have smaller temperature variations between seasons and between day and night. Summers are warm but rarely extremely hot; winters are mild but not bitterly cold. Rainfall can be a risk, especially near harvest.

Wine effect: Long, gentle growing seasons allow slow ripening and complexity development. But the lack of extreme heat means late-ripening varieties may struggle in cooler years, and autumn rain can be a major problem.

Examples: Bordeaux, Loire Valley, Rías Baixas, Margaret River, parts of New Zealand

Risks: Rain during harvest (dilution, rot), cloud cover reducing sunlight, humidity and fungal disease

Mediterranean Climate

Characterised by warm to hot, dry summers and mild, wet winters. This is often considered the ideal pattern for viticulture because it delivers reliable warmth during the growing season with low disease pressure (dry conditions discourage fungal disease), and the rain falls in winter when vines are dormant.

Wine effect: Reliable ripeness every year. Low disease pressure means less need for chemical spraying. However, dry summers may require irrigation, and extreme heat can be a problem.

Examples: Southern Rhône, most of southern France, coastal California, most of Chile, South Africa (Western Cape), much of Spain, Greece, southern Italy

Key insight: Some regions combine elements of different climate types. Burgundy, for example, is often described as having a continental climate with some maritime influence. Bordeaux is maritime but with Mediterranean tendencies in the south. Don’t treat these categories as rigid boxes, they’re reference points.

Macroclimate, Mesoclimate, and Microclimate

Climate operates at different scales, and the exam expects you to understand these three levels:

Scales of Climate
Macroclimate
The overall climate of a large area, a whole region, like "Bordeaux" or "the Barossa Valley." This is what weather stations measure and what maps show. It gives you the big picture but doesn’t capture local variations.
Mesoclimate
The climate of a specific site, a particular vineyard, hillside, or valley. Mesoclimate accounts for factors like altitude, slope, aspect (direction the vineyard faces), proximity to water, and shelter from wind. Two vineyards 5 km apart in the same region can have meaningfully different mesoclimates.
Microclimate
The climate in the immediate vicinity of the vine, within and around the canopy of leaves and fruit. This is affected by canopy management decisions (leaf removal, shoot positioning) and vine density. The microclimate around the grapes directly affects ripening, disease risk, and fruit quality.
Why this matters: A grower can’t change the macroclimate, can only partially choose the mesoclimate (by where they plant), but can significantly influence the microclimate through vineyard management. This is why canopy management is so important, it’s the grower’s primary tool for controlling conditions around the grapes.

Temperature

Temperature is the single most important climate factor for viticulture. It controls the rate at which grapes ripen and therefore has a direct impact on the style of wine produced.

Why Temperature Matters for Ripening

Day-Night Temperature Variation (Diurnal Range)

The difference between daytime highs and nighttime lows is called the diurnal range. A large diurnal range (warm days, cool nights) is considered beneficial for wine quality because:

Regions with a large diurnal range include high-altitude vineyards (Mendoza, parts of Spain), continental climates (Burgundy), and areas influenced by cold ocean currents or night-time fog (Sonoma Coast, parts of Chile).

Temperature extremes: Below about 10°C, vine growth stops. Above roughly 35°C, photosynthesis slows dramatically. Above 40°C, the vine shuts down entirely as a survival mechanism (closing its stomata to conserve water, which halts both photosynthesis and transpiration). Prolonged extreme heat can permanently damage fruit quality.

Sunlight

Sunlight serves two functions in the vineyard, and the exam expects you to distinguish between them:

Too much sunlight can be a problem in hot climates: grapes can get sunburned, developing bitter off-flavours or literally cooking on the vine. In very sunny, warm regions, growers may deliberately leave more canopy to shade the fruit zone.

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Exam Tip

Remember: sunlight on leaves drives photosynthesis and sugar production. Sunlight on fruit develops colour and reduces green characters. These are related but distinct effects. In cool climates, you generally want more sun exposure for both leaves and fruit. In hot climates, you may want sun on the leaves but shade on the fruit.

Rainfall and Water

Water is essential for the vine to grow and photosynthesise, but the timing and amount of water a vine receives has a profound effect on wine quality.

The Goldilocks Principle

Vines need some water stress to produce quality wine, but not too much or too little:

When Rain Falls Matters

The Mediterranean advantage: Mediterranean climates concentrate their rainfall in winter, leaving summers dry. This gives vines a reliable water supply to start the growing season while minimising the risks of rain during ripening and harvest. It’s one reason Mediterranean regions produce such consistent vintages compared to maritime regions like Bordeaux.

Humidity and Disease Risk

Humidity, moisture in the air, is primarily a concern because of its effect on vine disease:

This is why warm, humid regions (like parts of South America’s Atlantic coast or southeastern Australia) face different viticultural challenges than warm, dry regions (like inland Spain or central Chile).

Noble rot vs grey rot: Botrytis cinerea is the same fungus whether it’s welcome or not. In humid conditions with no drying periods, it causes destructive grey rot, ruining grapes. But in certain specific conditions, morning mists followed by warm, sunny afternoons that dry the grapes (as in Sauternes, Tokaj, and parts of the Loire), botrytis develops in its beneficial "noble" form, concentrating sugars and adding honeyed, marmalade complexity to sweet wines.

Altitude, Aspect, and Slope

These are mesoclimate factors, they create significant local variations within a broader region.

Altitude

Temperature drops by roughly 0.6°C for every 100 metres gained in elevation. This is why altitude is such a powerful tool in warm and hot climates:

  • In Mendoza (Argentina), vineyards range from about 600m to over 1,500m above sea level. Higher-altitude vineyards produce fresher, more acidic, more elegant wines.
  • In Etna (Sicily), vineyards at 700–1,000m produce strikingly different wine from those at 300m, despite being in the same region.
  • Higher altitude also means more intense UV light, which can promote thicker grape skins (more colour, tannin, and flavour compounds).
  • Altitude increases the diurnal range, warm days but significantly cooler nights, preserving acidity.

Aspect (Which Direction the Vineyard Faces)

In the Northern Hemisphere, south-facing slopes receive more direct sunlight and are warmer. This is critical in cool climates like Germany, Burgundy, and Alsace, where south-facing slopes may be the only sites warm enough to ripen grapes fully. North-facing slopes are cooler and shadier.

In the Southern Hemisphere, the reverse is true: north-facing slopes are the warm ones.

East-facing slopes catch the morning sun (warming the vines early, which helps in frost-prone areas). West-facing slopes catch the afternoon sun (maximum heat, but can be too warm in hot climates).

Slope

Sloped vineyards have several advantages over flat land:

  • Better drainage: water runs downhill, preventing waterlogging
  • More direct sunlight: angled slopes receive sunlight more directly, increasing warmth
  • Cold air drainage: cold air is denser than warm air and flows downhill. Vineyards on mid-slopes often avoid frost because cold air drains down to the valley floor. The valley floor, where cold air collects, is called a "frost pocket."

The downside: steep slopes are much more expensive to work. Machinery often can’t be used, so everything must be done by hand. This increases labour costs significantly. The terraced vineyards of the Mosel, Douro, and northern Rhône are beautiful but extremely costly to maintain.

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Exam Angle

Altitude, aspect, and slope questions are always about cause and effect. Don’t just state that a vineyard is south-facing, explain why that matters: "The south-facing aspect maximises sun exposure in this cool continental climate, ensuring grapes receive enough warmth and light to achieve full ripeness while retaining acidity."

Other Climate Influences

Proximity to Water

Large bodies of water (oceans, lakes, major rivers) moderate temperatures. Water heats and cools more slowly than land, so coastal or lakeside vineyards experience less extreme temperature swings. The Gulf Stream warms western Europe and makes viticulture possible in places like Bordeaux and the Loire that would otherwise be too cold. Lake-effect warming (e.g., Lake Geneva for Swiss vineyards, the Great Lakes for Ontario’s Niagara Peninsula) can extend the growing season.

Cold ocean currents, conversely, can cool coastal areas. The Humboldt Current along Chile’s coast and the Benguela Current off South Africa’s west coast both create cool conditions near the shore, allowing quality viticulture at surprisingly low latitudes.

Wind

Wind effects are varied:

  • Cooling effect: wind lowers vine temperature, which can be beneficial in warm climates (slowing ripening, preserving acidity) or harmful in cool climates (chilling the vines and inhibiting ripening)
  • Drying effect: wind dries moisture from vine surfaces, reducing fungal disease pressure. This is extremely valuable in humid regions.
  • Frost protection: gentle breezes can prevent cold air from settling, reducing frost risk
  • Damage: strong persistent winds can break shoots, damage canopy, and stress vines. Windbreaks (trees, walls) are sometimes planted to protect vineyards.

Named winds to know: the Mistral (cold, dry wind in the southern Rhône, dries vines but can damage them) and the Zonda (hot, dry wind in Mendoza).

Fog and Mist

Morning fog and mist cool vineyards and reduce sunlight in the morning, then burn off to allow afternoon sunshine. This pattern is common in coastal California (Sonoma, Carneros), the Casablanca Valley in Chile, and parts of South Africa. It creates a natural temperature-regulating system that can extend the growing season and preserve acidity in otherwise warm climates.

Fog also promotes humidity around vine surfaces, which can encourage botrytis, destructive in most contexts, but essential for the production of certain sweet wines.

Soil

Soil influences wine in several important ways, though the extent to which soil directly flavours wine is debated. What is not debated is that soil affects vine health, water supply, and temperature, all of which clearly affect wine quality and style.

Key Soil Properties

Drainage and Water-Holding Capacity

This is the most important property of any vineyard soil. The soil needs to supply the vine with water throughout the growing season, but not too much water at any one time.

  • Well-drained soils (gravel, sand, limestone over rock), water passes through quickly. The vine’s roots must grow deep to find water, which can moderate vigour and encourage concentration. Bordeaux’s famous gravel banks and Burgundy’s limestone slopes are examples.
  • Water-retentive soils (clay), hold moisture well, providing a steady supply. This can be beneficial in dry climates (acting as a reservoir) but problematic in wet climates (waterlogging and excessive vigour). Clay is the dominant soil on Bordeaux’s Right Bank, where Merlot thrives partly because its roots can access this consistent water supply.

Heat Retention

Some soils absorb and radiate heat better than others:

  • Dark-coloured soils (e.g., slate in the Mosel) absorb sunlight and radiate warmth back to the vines, which aids ripening in cool climates
  • Stony/gravelly soils absorb heat during the day and release it at night, extending the effective warm period
  • Light-coloured soils (e.g., chalk, limestone, albariza in Jerez) reflect sunlight upward onto the vine, increasing light exposure to the fruit zone

Nutrient Content (Fertility)

Counter-intuitively, highly fertile soils are generally not desirable for quality wine production. Fertile soils promote vigorous growth, the vine puts energy into producing shoots and leaves rather than concentrating flavour in its fruit. The best vineyard soils tend to be relatively poor and infertile, forcing the vine to struggle slightly and focus on fruit quality.

This is why many famous vineyard soils are rocky, chalky, or gravelly, they are low in nutrients but have excellent drainage, which forces vine roots to grow deep in search of water and minerals.

Common Soil Types in Wine Regions

Major Soil Types and Their Properties
Gravel
Excellent drainage, retains and radiates heat. Bordeaux Left Bank, Graves, Gimblett Gravels (NZ).
Clay
High water retention, cooler, more fertile. Bordeaux Right Bank (Pomerol), parts of Barossa Valley.
Limestone / Chalk
Good drainage, high pH (alkaline), reflects light. Burgundy, Champagne, Chablis, parts of Saint-Émilion, Jerez (albariza).
Slate
Absorbs and retains heat, good drainage on slopes. Mosel (Germany), Douro (Portugal).
Sand
Very well-drained, low fertility, phylloxera cannot move through it. Colares (Portugal), some Barossa vineyards.
Volcanic
Mineral-rich, well-drained, often with good water retention. Etna (Sicily), Canary Islands, Tokaj (Hungary).
Loam
Mix of sand, silt, and clay. Fertile, good for vigorous growth. Common in high-volume wine regions; less suited for premium quality.

Terroir: The Complete Picture

Terroir is a French concept with no perfect English equivalent. It refers to the complete set of natural environmental factors that give a wine its sense of place. Terroir combines:

The concept of terroir is central to European wine philosophy and is the foundation of appellation systems like France’s AOC/AOP. The idea is that wines from a specific place should express characteristics unique to that place, characteristics that cannot be replicated elsewhere, no matter how skilled the winemaker.

Not all wine traditions emphasise terroir equally. New World wine regions have historically placed more emphasis on grape variety and winemaker skill, though there is a growing movement toward terroir-driven winemaking in Australia, California, Chile, and other New World countries.

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Exam Tip

If asked about terroir, don’t just define it, give a concrete example. "The terroir of the Côte d’Or in Burgundy combines a continental climate with limestone and marl soils on east-facing slopes, creating conditions uniquely suited to Pinot Noir and Chardonnay. This specific combination of climate, soil, and topography produces wines that cannot be replicated elsewhere, even using the same grape varieties."

What the Exam Expects You to Know

Active Recall Prompts

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