Weather in Chamonix-Mont-Blanc in May

Shoulder season. May is shoulder season in Chamonix-Mont-Blanc — cheaper, quieter, and a genuine gamble. You should expect rain on 18 days of the month, which is more days wet than dry.

May ranks 6 of 12 in Chamonix-Mont-Blanc: past the worst of the year but short of September, which is the month to book if the dates are open.

Rain on 18 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 16.2 °C days and 6.3 °C nights; the spread matters more here than any single number.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest May day reached 29.1 °C and the coldest night fell to -3 °C, and the wettest single day dropped 56 mm — roughly 48% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 182 mm against 62 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 117 mm average is a reasonable planning figure, not a promise.

Wind is light at 2.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 79%, high enough to notice on the warm days without dominating them.

How May sits in the year

The month is on the way up: 4.7 °C warmer than April, and June adds another 4.2 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short. Rain has already shifted: 5 days more than April had.

Daylight in May

14.9 hours of daylight, gaining 1.2 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

Shoulder. The value months — prices ease off and you get the place closer to itself.

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

May in Chamonix-Mont-Blanc versus nearby

If Chamonix-Mont-Blanc is one option among several, the nearby comparison is worth making. Annecy is a better bet in May — 2.9 °C warmer, 2 days less rain. Zermatt is the weaker option in May — 3.9 °C cooler, the same number of rain days.

So: May is a compromise. September is 20 points better and is what Chamonix-Mont-Blanc is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Chamonix-Mont-Blanc

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