Weather in Chamonix-Mont-Blanc in August

A good month. August works. It is not the peak, but nothing about it fights you. You should expect rain on 15 days of the month, which is more days wet than dry.

August ranks 2 of 12 in Chamonix-Mont-Blanc. Only September scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 15 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest August day reached 32.7 °C and the coldest night fell to 4.4 °C, and the wettest single day dropped 46 mm — roughly 44% of the month's rain in one day.

August is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest August on record still delivered 171 mm against 49 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 105 mm average is a reasonable planning figure, not a promise.

Wind is light at 2.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 74%.

How August sits in the year

Temperatures hold steady either side: 22.2 °C in July, 22.1 here, 18.8 in September. Nothing about the timing within the month matters much.

Daylight in August

14.2 hours of daylight, losing 1.4 hours across the month. That is between Chamonix-Mont-Blanc's extremes of 15.7 and 8.7 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 28.9 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage. At 1060 m the air is thin enough to matter — sun that burns faster than the temperature suggests, and nights that cool off quickly.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in Chamonix-Mont-Blanc versus nearby

If Chamonix-Mont-Blanc is one option among several, the nearby comparison is worth making. Annecy is close enough to be a coin toss — 3.8 °C warmer, 2 days less rain. Zermatt is close enough to be a coin toss — 3.6 °C cooler, the same number of rain days.

So: August is effectively as good as it gets here — 1 points behind September, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Chamonix-Mont-Blanc

See all twelve months in Chamonix-Mont-Blanc, or where else to go in August.