Weather in Leiria in September

Prime time. If you get to pick your dates, September is the one. Highs average 28.3 °C, lows 15.7 °C, and rain falls on 5 days — nothing in the month is working against you.

September ranks 4 of 12 in Leiria: past the worst of the year but short of June, which is the month to book if the dates are open.

Rain falls on only 5 days, so an itinerary with no wet-weather fallback is a reasonable risk. Pack for 28.3 °C days and 15.7 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 10 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 39 °C and the coldest night fell to 10.7 °C.

This is the volatile part. September rainfall has ranged from 1 mm to 115 mm across the twenty years measured — a 114 mm spread around an average of 31 mm. The average is real but almost no individual September looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind is light at 6.8 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 69%.

How September sits in the year

The month is on the way down: 1.9 °C cooler than August, with October dropping another 4.6 °C. The first week and the last are not the same trip. Rain is the thing that moves: October brings 6 days more of it, so the earlier half of a flexible trip is the safer half.

Daylight in September

12.5 hours of daylight, losing 1.3 hours across the month. That is between Leiria's extremes of 15 and 9.4 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 19.8 °C in September — swimmable, but it takes a moment to commit. 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 Leiria versus nearby

If Leiria is one option among several, the nearby comparison is worth making. Aveiro is close enough to be a coin toss — 2.6 °C cooler, 1 day more rain. Lisbon is close enough to be a coin toss — 6 °C cooler, the same number of rain days.

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

Every month in Leiria

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