Although it's not an island like its neighbour across the English Channel, France is bordered on three sides by water. The Atlantic and Mediterranean help to moderate the temperature swings that otherwise might occur at France's latitude. The ragged northwest coast of Brittany and Normandy has a climate not too dissimilar to much of Great Britain, a little milder and wetter than London's. Toward the heart of France – Paris to the Loire Valley and east toward Strasbourg – you'll find a bit more variety. Despite its reputation for sultriness (and apart from rare events like the brutal 2003 heat wave), central France is typically very pleasant in mid-summer, with highs typically below 26°C/79°F. Winters do tend to be grey and damp, with plenty of fog from late autumn onward. Occasional Siberian onslaughts can cause readings to plummet well below 0°C/32°F for several days.
Since the land rises to the south as one approaches the Massif Central and the Alps, the winters here can be just as cold as further north, although the distance from the sea allows for brighter weather in summer. Summer storms can be intense throughout the easternmost provinces. Towns at higher elevation, such as Le-Puy-en-Velay in the Massif and Grenoble in the Alps, can be nippy on summer evenings and downright frigid in January. They compensate with strong daytime warm-ups on sunny days, especially toward Provence. Even in winter, warm winds descending the Pyrenees can bring a spell of days above 20°C/68°F to the Gascogne region, including Toulouse. Summer on France's Mediterranean coast is almost rain-free, with stray showers along parts of the coast about once per week. Marseilles' July temperatures are almost identical to those in Los Angeles, without the blasts of 40°C/104°F heat that sometimes bake LA. Winter on the Cote d'Azur (including Monaco) is equally easy to take: temperatures normally reach 10°C/50°F even in January, and it only rains about every third or fourth day.
The fly in the ointment is the infamous mistral, a bitter, grating north wind – sometimes exceeding 100kph/60mph – that descends from the Alps. It's most frequent and intense from November into April along the coast from Toulon to Marseilles. The mistral often arrives abruptly, plays out in a day or two, and is usually followed by sunshine and a warming trend. Toward the Pyrenees and the west coast, the climate is a blend of Atlantic and Mediterranean. Showers are frequent and sometimes heavy but seldom severe. To the south, the Pyrenees are high enough and close enough to the sea to make for a surprising amount of snow and cold at their highest elevations, although they sit above the pools of fog and gloom that hug the Atlantic coast. Halfway up the west coast, the region around La Rochelle manages to combine the sunshine of Aquitane with the more even-tempered quality of Brittany, making for a particularly smooth climatic blend.