Weather in Naples in September

A good month. September is a solid month to be in Naples. Highs average 28 °C, lows 18.4 °C, and rain falls on 10 days — nothing in the month is working against you.

September ranks 5 of 12 in Naples: past the worst of the year but short of May, which is the month to book if the dates are open.

Rain on 10 days, 2 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: 7 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 37.3 °C and the coldest night fell to 10.9 °C, and the wettest single day dropped 36 mm — roughly 53% of the month's rain in one day.

September is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest September on record still delivered 132 mm against 33 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 68 mm average is a reasonable planning figure, not a promise.

Wind is light at 6.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 67%.

How September sits in the year

The month is on the way down: 5.3 °C cooler than August, with October dropping another 4.4 °C. The first week and the last are not the same trip. Rain has already shifted: 5 days more than August had.

Daylight in September

12.5 hours of daylight, losing 1.3 hours across the month. That is between Naples's extremes of 15.1 and 9.3 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 24.9 °C in September — warm enough to stay in as long as you like. This is the warmest the water gets all year.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

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

September in Naples versus nearby

If Naples is one option among several, the nearby comparison is worth making. Positano is close enough to be a coin toss — 3.6 °C cooler, 1 day more rain. Rome is close enough to be a coin toss — within a degree on temperature, 1 day less rain.

So: September works, with May the better month by 7 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Naples

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