Climate averages 1991–2020
Porto weather
in September.
A warm, moderately wet month: the 3rd warmest and the 4th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Porto: daytime highs average 24.1°C and nights cool to about 15.7°C. By daytime temperature it is the 3rd warmest of the 12 months.
Expect about 64 mm of rain on roughly 7 days, which makes September a moderately wet month (the 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 31 min on an average September day.
The nearest other city in this atlas is Braga (47 km away). In September its highs average 23.8°C, about as warm as Porto, with 79 mm of rain.
Among the 12 cities listed in Portugal, Porto ranks 10th of 12 for the warmest September highs and 10th of 12 for the driest September (rainfall, lowest first). The mean September high of those 12 cities is 24.6°C; Porto is 0.5°C cooler than that mean.
From September to October, average highs fall by 4.0°C to 20.1°C, and monthly rainfall rises from 64 mm to 166 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Porto climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 12.8°C6.3°C | 6.3°C | 150 | 12.2 | 9.610 h |
| February | 13.9°C6.3°C | 6.3°C | 103 | 9.6 | 10.611 h |
| March | 16.3°C8.1°C | 8.1°C | 121 | 10.2 | 11.912 h |
| April | 17.5°C9.7°C | 9.7°C | 121 | 11.8 | 13.313 h |
| May | 20.1°C12.3°C | 12.3°C | 101 | 11.1 | 14.514 h |
| June | 23.2°C15.0°C | 15.0°C | 40 | 6.3 | 15.115 h |
| July | 25.6°C16.7°C | 16.7°C | 23 | 4.0 | 14.815 h |
| August | 26.2°C17.2°C | 17.2°C | 29 | 4.5 | 13.814 h |
| September, selected | 24.1°C15.7°C | 15.7°C | 64 | 6.6 | 12.513 h |
| October | 20.1°C13.1°C | 13.1°C | 166 | 12.7 | 11.111 h |
| November | 15.7°C9.6°C | 9.6°C | 163 | 12.9 | 9.910 h |
| December | 13.5°C7.4°C | 7.4°C | 167 | 12.4 | 9.39 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Braga in SeptemberPortugal · 47 kmHigh 23.8°C · Low 13.7°C · 79 mm rain
- Aveiro in SeptemberPortugal · 56 kmHigh 25.1°C · Low 15.8°C · 51 mm rain
- Viseu in SeptemberPortugal · 80 kmHigh 24.3°C · Low 13.7°C · 66 mm rain
- Coimbra in SeptemberPortugal · 106 kmHigh 26.3°C · Low 15.0°C · 49 mm rain
- Vigo in SeptemberSpain · 121 kmHigh 22.0°C · Low 14.6°C · 88 mm rain
- Pontevedra in SeptemberSpain · 143 kmHigh 23.3°C · Low 14.8°C · 84 mm rain
- Ourense in SeptemberSpain · 146 kmHigh 24.4°C · Low 13.5°C · 48 mm rain
- Leiria in SeptemberPortugal · 157 kmHigh 25.3°C · Low 15.7°C · 41 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Porto) is explained once on the Porto year overview and on the Sources, method and limits page.