2.2 Climate Types and Vintage Weather

2.2 Climate Types and Vintage Weather

Quick Answer: Climate is the long-term temperature and rainfall pattern of a region; weather is what happens in a given year. WSET classifies climates by warmth (cool, moderate, warm, hot) and by pattern (Mediterranean, maritime, continental). Latitude, altitude, oceans, continentality, and diurnal range refine the picture and explain why neighbouring regions can produce very different wines.

Climate vs Weather

Climate is the multi-year average of temperature, rainfall, sunshine, and humidity that defines what varieties can ripen reliably. Weather is the short-term variation within a vintage—a late frost, a wet flowering, a heatwave at harvest. Climate sets the stylistic baseline; weather explains why 2018 and 2021 from the same appellation can taste and price differently.

Warmth Categories (Cool → Hot)

WSET Level 3 expects you to associate growing-season warmth with ripening outcomes.

Cool climates (e.g. Champagne, Mosel, Central Otago in many seasons) preserve acidity and fresh aromatics but struggle in cold years. Moderate climates (much of Bordeaux, Tuscany’s better sites, parts of Sonoma) allow Cabernet, Sangiovese, or Chardonnay to reach balance. Warm climates (Barossa, Priorat, parts of Napa) push ripeness and body. Hot climates (inland Australia, Central Valley California, parts of southern Spain) need heat-tolerant varieties, irrigation, and careful harvest timing to avoid flat, overripe wines.

Mediterranean, Maritime, and Continental Patterns

Beyond average warmth, rainfall timing and temperature extremes matter.

Mediterranean

Warm, dry summers and mild, wetter winters. Low summer rainfall reduces fungal disease pressure but increases drought stress—irrigation or deep-rooted vines may be needed. Classic examples include coastal California, much of South Australia’s premium zones in a broad sense, Central Chile’s summers, and the Mediterranean basin. Dry summers favour ripe, healthy fruit when water is managed.

Maritime

Oceans moderate temperature: cooler summers, milder winters, and rainfall more evenly spread through the year. Humidity and autumn rain raise rot risk near harvest (think Bordeaux and much of New Zealand). Maritime climates can be cool or moderate overall; the key signature is moderation plus rainfall timing that challenges late ripening.

Continental

Large landmasses create hot summers and cold winters, with a shorter, sharper growing season. Spring frost and winter freeze are serious hazards; summers can ripen fruit quickly. Examples include parts of inland Spain, Central Europe, Washington State’s Columbia Valley, and Argentina’s high valleys in a continental-influenced sense. Large diurnal ranges often accompany continental or high-altitude sites.

Regional Climate Factors

Even within one warmth band, geography rewrites the climate.

Latitude

Higher latitudes receive less intense solar energy and have longer summer day length in the growing season. Cool-climate viticulture clusters toward the poles of the wine map (roughly 30–50° latitude in each hemisphere). Lower latitudes are warmer unless altitude or cooling influences compensate.

Altitude

Temperature falls with elevation (roughly 0.6°C per 100 m as a rule of thumb). High vineyards in Argentina, Priorat’s upper slopes, or Etna can be cool despite low latitude. Altitude often increases UV intensity (thicker skins, colour) and diurnal range.

Oceans and Lakes

Large water bodies store heat and release it slowly, moderating extremes. Sea breezes can cool afternoon heat (Carneros, Casablanca, Rías Baixas). Lakes may reduce frost risk by warming cold air (Finger Lakes) or increase humidity. Cold ocean currents (Humboldt Current off Chile/Peru; California Current) create notably cool coastal climates at surprisingly low latitudes.

Continentality

Continentality measures the difference between summer and winter (or day and night in related discussions). High continentality means hot summers and cold winters—fast ripening windows and frost/freeze risk. Low continentality (maritime) means a longer, gentler season.

Diurnal Range

Diurnal range is the gap between daytime high and nighttime low temperatures. Warm days build sugar; cool nights slow acid respiration and help retain freshness and aromatics. Desert and high-altitude vineyards often show large diurnal ranges (Mendoza, Columbia Valley). Small diurnal ranges in constantly warm coastal or tropical-edge sites can produce lower-acid fruit unless harvested early.

Vintage Weather Variation

Climate predicts what is possible; weather decides what happens this year.

• Spring frost after budburst destroys primary shoots → lower yields; secondary buds may give partial crop of different quality.
• Wet flowering → coulure/millerandage → low, uneven yields.
• Drought mid-season → small berries, concentration, or arrested ripening if extreme.
• Heatwaves → rapid sugar rise, sunburn, possible shutdown of vines during extreme heat.
• Harvest rain → dilution, rot, selective picking, or quality collapse in marginal years.

Vintage charts matter commercially: a celebrated warm, dry year can lift prices and ageing reputation; a wet year may force early picking, chaptalisation where legal, or declassified volume. For the exam, always connect the weather event to sugar, acid, disease, or yield—not just “bad weather.”

Worked Exam Scenario

Two regions at similar latitude: one maritime (Bordeaux Left Bank) and one more continental-inland. In a cool, wet vintage the maritime site risks rot and dilution for late Cabernet; the continental site may still ripen if summer heat is adequate but faces frost in other years. Same latitude band; pattern and weather diverge. Separately: cool-climate Riesling in a cool year stays high-acid and light; warm-climate Shiraz in a hot year becomes high-alcohol and very ripe—climate category predicts the default style before human choices intervene.