Weather and Climate in Wine Regions: Rain, Heat and Frost

Of the 336 destination-months in our climate table, 41 are hard. In 28 of them the average afternoon stays under 10 °C, in 9 the month brings 120 mm of rain or more, and in 4 the average high is above 33 °C. Rain, the thing most people plan around, causes far fewer hard months than cold does. Tuscany and Chianti share one weather station, so that count includes the same month twice.

The figures are official 30-year normals for 28 destinations. They cover 1991-2020 everywhere except Marlborough, where the only official normal we could open is 1981-2010. Thirteen of the 28 come from a stand-in station outside the wine zone, marked in each table. Santorini is missing, and the reason is below. This page is the climate half of our guide to when to go. The harvest half is on harvest season, and what to put on is on what to wear and pack.

We sorted the 28 destinations into four groups by the shape of the year: when the rain falls and how far the highs travel. The grouping is ours. The numbers in every table are the agencies'. The boxes leak, and the Comite Champagne says why for its own region: it describes a dual climate with both oceanic and continental influences, and an average annual temperature of 11 °C (Comite Champagne, climate page).

Each table gives the station, the warmest month by average daily high, the wettest and driest month by rainfall, and the hard months with their cause. Hard means an average high above 33 °C or under 10 °C, or 120 mm of rain or more. The criteria are explained further down.

Almost no rain in July, a wet autumn or winter. Setubal, south of Lisbon, averages 2.1 mm in July and 3.2 mm in August, and Napa State Hospital 0.0 mm in July. The southern hemisphere runs the same pattern on the mirror calendar: Cape Town airport has 9.4 mm in January and 92.3 mm in June, Cape Naturaliste 7.5 mm in February and 142.0 mm in July. The price of the dry summer is heat. Sicily's plain and the Douro stand-in are the only places in the whole set where the average afternoon passes 33 °C. Penedes, Maipo and the Cape tie for the most mild and dry months, ten of twelve. Tuscany and Chianti have three.

The stand-ins in this group: Siena for Tuscany and Chianti, 20 to 40 km from Chianti Classico on the same kind of hills. Grazzanise, on the Volturno plain, for Campania, where the Irpinian hills run cooler. Sigonella, on the Catania plain, for Sicily, where the Etna vineyards sit at 400 to 1,000 m and run cooler. Mirandela, in the Tua valley, for the Douro. Reus airport for Penedes and Priorat. Cape Town airport, on the coast, for the Cape Winelands. Cape Naturaliste, on the northern coast of the zone, for Margaret River. Pudahuel in Santiago for Maipo, where coastal Casablanca runs cooler. Santorini is out because the Hellenic National Meteorological Service publishes 1991-2020 average highs for its Santorini station but no monthly rain, and the other normals we opened do not cover the island. We did not fill the gap from a few recent years.

Sources, one per station:

• LaMMA, Siena, 1991-2020
• Aeronautica Militare via WMO normals, Grazzanise
• Aeronautica Militare via WMO normals, Catania Sigonella
• Meteo-France, Aix-en-Provence
• Meteo-France, Orange
• IPMA, Mirandela
• IPMA, Setubal
• AEMET via WMO normals, Reus airport
• NOAA NCEI, Napa State Hospital
• BoM, Nuriootpa
• SAWS via WMO normals, Cape Town airport
• BoM, Cape Naturaliste
• DMC Chile via WMO normals, Pudahuel

Bordeaux has no hard month and 925 mm of rain a year, second only to Waiheke's 1,119 mm (Auckland airport, standing in for the island). The Yarra Valley's rain stays between 46 and 72 mm in every month, so there is no dry season to count on. Marlborough has no hard month either, and its wettest month, July, is 75.3 mm. That normal is 1981-2010, which makes it the one row on this page from an older period.

Waiheke is an island with its own microclimate, and Auckland airport is across the Hauraki Gulf: read its numbers as the climate of the gulf. Marlborough's source is the World Meteorological Organization's city page, fed by MetService. We could not open the newer 1991-2020 normal.

Sources:

• Meteo-France, Bordeaux-Merignac
• BoM, Coldstream
• MetService via WMO World Weather Information Service, Blenheim
• NIWA via WMO normals, Auckland Aero

Veneto's average high travels from 7.0 °C in January to 30.4 °C in July, a spread of 23 degrees. Mendoza gets 238 mm of rain in a whole year, and its January average runs from a 19.3 °C low to a 32.8 °C high. Kakheti's wettest month is May, at 119.1 mm: 0.9 mm under our hard line. Rioja's wettest month is 46.6 mm. The Hunter Valley sits here for its summer: February is its wettest month at 99.0 mm, and Hunter Valley Wine and Tourism says the heaviest rainfall is in summer, with intermittent thunderstorms. Harvest there is covered on harvest season.

Mondovi, in the Piedmont foothills about 35 km from the Langhe, stands in for Langhe and Barolo, because Alba and Cuneo have no 1991-2020 normal we could open.

Sources:

• Aeronautica Militare via WMO normals, Verona/Villafranca
• Aeronautica Militare via WMO normals, Mondovi
• AEMET via WMO normals, Logrono airport
• Georgia NEA via WMO normals, Telavi
• SMN Argentina via WMO normals, Mendoza airport
• BoM, Cessnock airport
• Hunter Valley Wine and Tourism, weather and climate

Champagne's warmest month, July, averages 25.5 °C, and its rain never passes 78.4 mm in any month. Burgundy's highest is 77.6 mm. In both, cold alone makes the hard months, November to February. Niagara's five hard months run November to March, with a January average high of 0.2 °C. In the Okanagan the January high is 1.6 °C, and the whole year brings 344 mm of rain, with 43.8 mm in June as its wettest month.

Dijon, about 40 km from the Cote d'Or, stands in for Burgundy because Beaune has no 1991-2020 sheet. Vineland, an Environment Canada station on the Niagara Peninsula about 25 km from Niagara-on-the-Lake, stands in for it. Both Canadian rows are composite series that the agency stitches from an old station and its successor.

Sources:

• Meteo-France, Bouzy
• Meteo-France, Dijon-Longvic
• Environment Canada, Vineland
• Environment Canada, Penticton A

Rain is hard in only nine cells: Napa State Hospital from December to February (126.5, 130.3 and 140.5 mm), Cape Naturaliste in June and July (127.7 and 142.0 mm), Auckland airport in July (136.9 mm), Siena in November (125.0 mm, which counts twice for Tuscany and Chianti) and Grazzanise in November (151.7 mm, the highest monthly figure among the stations in the first four tables). Everything that follows in this section is our judgment, not a sourced rule.

Cellar visits and indoor tastings go ahead in the rain. What rain removes is the part of the day that was outdoors: the walk between the rows, the terrace, the bike, the open vehicle. Before you book in a wet month, ask what the wet-weather version of the vineyard stop is. A tour that has an answer is a better buy in a Tuscan November than one that does not. We would skip a bike or open-vehicle tour in the wet months listed above unless the listing names a covered alternative.

Monthly totals hide how the rain arrives. 70 mm in two storms and 70 mm over twelve days weigh the same in these tables and make very different days. The dataset has no count of rainy days.

Our line is an average daily high above 33 °C. Two places cross it: the Catania plain in July and August (34.0 and 34.5 °C at Sigonella) and the Douro stand-in Mirandela (33.4 and 33.2 °C). An average of daily highs means plenty of afternoons run hotter than that. Just under the line, the 29 to 33 °C band holds Orange and Aix-en-Provence in July (31.1 and 31.0 °C), Grazzanise in August (31.5 °C) and Mendoza in January (32.8 °C).

In that band we would put the vineyard stop before noon and the cellar after lunch, and we would ask whether the tasting is under a roof. Sun protection has its own section on what to wear and pack. Pacing a day, whatever the temperature, is on a day of tasting.

The Comite Champagne says continental influences can bring freezing temperatures in winter without warning, and that temperatures below -10 °C have been recorded, with frosts that can be devastating for the vineyards (Comite Champagne). Put the table beside that sentence. The average January low at Bouzy is 1.1 °C. An average never shows the cold snap, and the committee's sentence does.

For a visitor the plain fact is the winter itself. In Champagne the average high is 5.8 °C in January and 6.3 °C in December. In Niagara it is 0.2 °C in January, and in the Okanagan 1.6 °C. Those are winter trips: layers, closed shoes, and a tour that does not depend on a terrace.

Icewine is the extreme case. Our what to wear page attributes a picking threshold of -8 °C to Wine Country Ontario. That site refused our connection today, so we have not rechecked the figure for this page and do not offer it here as verified. The normals in this dataset hold no snowfall, so we say nothing about snow depth or road conditions.

Climate normals do not record smoke, so the dataset is silent. The California fire-season dates from CAL FIRE are on Napa or Sonoma, and we do not repeat them. For Australia we did not open an official source on smoke, so we give no claim. If your dates fall in a region's dry, hot months, read the cancellation terms before you book: that advice is ours, and it costs nothing.

No. It is a climate label and nothing more. A month is mild and dry when the average high is between 15 and 29 °C and the rain is under 80 mm. It is hard when the high is above 33 °C or below 10 °C, or the rain is 120 mm or more, and hard wins when a month qualifies for both. Everything else is workable: highs of 10 to 15 °C or 29 to 33 °C, or 80 to 120 mm of rain.

Of the 336 destination-months, 179 are mild and dry, 116 workable and 41 hard. The label is not harvest, crowds or closures. A mild October can be the month the cellar doors are fullest, and our when-to-go guide is where the months are laid side by side. We never write best time.

The weak part of the criterion is the 80 mm line. Move it to 60 mm and 64 of the 336 cells change class, 19 percent. Move it to 100 mm and 21 change. Temperatures are steadier: raising the hot line from 33 to 34 °C changes 3 cells, and lowering the top of the mild range from 29 to 28 °C changes 11. Niagara loses 6 cells at 60 mm, Burgundy and the Yarra 5 each. Several cells sit on the line: Langhe in May (80.5 mm), Verona in September (84.5 mm) and October (79.4 mm), Mirandela in October (73.8 mm). Read mild and dry as under 80 mm of rain, not as dry.

Because altitude, distance from the sea and a hillside move an average by several degrees, and thirteen of our 28 rows are stand-ins. This is the uncomfortable part of the page. In the five regions below we could open a second station, and the two disagree enough to change a label.

Under one Douro station July is hard, under the other it is mild and dry. We use Mirandela as the valley-floor reference, and neither station sits in the valley of the Douro. Enna is not on Etna either: it is simply the cooler second station we could open. The Cape Winelands row is the weakest on the page. Cape Town airport, on the coast, is the only SAWS station with a 1991-2020 normal we could open. The inland valleys run warmer in summer, and no official source we found says by how much, so some of the Cape's ten mild and dry months may be warmer than 29 °C in a valley.

Second-station sources:

• IPMA, Vila Real
• DMC Chile via WMO normals, Rodelillo Vina del Mar
• NOAA NCEI, Calistoga
• Aeronautica Militare via WMO normals, Enna
• BoM, Busselton airport

Our rule: if a hard month decides your trip, read the station note under its table before you read the label. The wrong station can flip it.

Every temperature and rainfall figure comes from an official normal that we opened and saved: the monthly average of daily highs and the monthly rainfall total, taken from the files linked under the tables. NOAA figures were converted from Fahrenheit and inches. Classes follow the criteria above and were recomputed from the saved files, with no value typed by hand. The Comite Champagne statements were read on the day of writing. Two things we could not confirm: the Wine Country Ontario icewine figure, and a 1991-2020 normal for Santorini. The grouping into four climate types, the advice on rain and heat, and the readings of the tables are our judgment. We use no figure from a single year and none from Wikipedia.

• Comite Champagne: Champagne and its climate
• LaMMA Regione Toscana: climate of Siena
• Meteo-France: Bouzy climate sheet 1991-2020
• IPMA: Mirandela normal 1991-2020
• NOAA NCEI: U.S. Climate Normals, Napa State Hospital
• Bureau of Meteorology: Cessnock airport 1991-2020
• Environment Canada: Penticton A normal
• WMO World Weather Information Service: Blenheim

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