Weather in Nantes in September

Prime time. September is about as good as Nantes gets. Highs average 22.2 °C, lows 11.3 °C, and rain falls on 8 days — nothing in the month is working against you.

September is the highest-scoring month of the twelve. The nearest rival is July, and the month at the other end of the year is January.

Rain on 8 days, 1 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

Averages flatten a month, and this one hides a few things: it never really gets hot: not one day in an average September reaches 30 °C. Across the twenty years measured, the hottest September day reached 31.6 °C and the coldest night fell to 3.6 °C, and the wettest single day dropped 30 mm — roughly 67% of the month's rain in one day.

September is moderately variable: 12 mm in the driest year against 121 mm in the wettest, around an average of 45 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 9.2 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 77%, high enough to notice on the warm days without dominating them.

How September sits in the year

The month is on the way down: 2.3 °C cooler than August, with October dropping another 4.2 °C. The first week and the last are not the same trip. Rain is the thing that moves: October brings 5 days more of it, so the earlier half of a flexible trip is the safer half.

Daylight in September

12.6 hours of daylight, losing 1.7 hours across the month. That is between Nantes's extremes of 15.9 and 8.5 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 19.4 °C in September — swimmable, but it takes a moment to commit. This is the warmest the water gets all year.

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.

September in Nantes versus nearby

If Nantes is one option among several, the nearby comparison is worth making. Bordeaux is close enough to be a coin toss — 2.9 °C warmer, 1 day more rain. Le Havre is close enough to be a coin toss — 3.2 °C cooler, 2 days more rain.

So: September is the answer for Nantes. If it is booked out or priced out, July is the next best thing at 2 points behind, and January is the month to keep off the shortlist.

Every month in Nantes

See all twelve months in Nantes, or where else to go in September.