Climate averages 1991–2020
São Luís weather
in September.
A hot, very dry month: one of the warmest and the driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in São Luís: daytime highs average 31.2°C and nights cool to about 25.5°C. By daytime temperature it is one of the warmest months of the year.
Expect about 11 mm of rain on roughly 3 days, which makes September a very dry month (the driest month of the year). Daylight, from sunrise to sunset, lasts about 12 h 06 min on an average September day.
The nearest other city in this atlas is São José de Ribamar (27 km away). In September its highs average 30.1°C, 1.1°C cooler than São Luís, with 11 mm of rain.
Among the 448 cities listed in Brazil, São Luís ranks joint 88th of 448 for the warmest September highs and joint 47th of 448 for the driest September (rainfall, lowest first). The mean September high of those 448 cities is 27.5°C; São Luís is 3.6°C warmer than that mean.
From September to October, average highs stay level at 31.2°C, and monthly rainfall rises from 11 mm to 13 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
São Luís climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 29.0°C24.7°C | 24.7°C | 221 | 25.4 | 12.212 h |
| February | 28.3°C24.4°C | 24.4°C | 305 | 26.3 | 12.212 h |
| March | 28.1°C24.2°C | 24.2°C | 440 | 30.3 | 12.112 h |
| April | 28.3°C24.3°C | 24.3°C | 414 | 28.8 | 12.112 h |
| May | 28.8°C24.6°C | 24.6°C | 286 | 26.9 | 12.012 h |
| June | 29.1°C24.7°C | 24.7°C | 153 | 23.0 | 12.012 h |
| July | 29.3°C24.7°C | 24.7°C | 103 | 20.0 | 12.012 h |
| August | 30.6°C25.3°C | 25.3°C | 28 | 9.0 | 12.012 h |
| September, selected | 31.2°C25.5°C | 25.5°C | 11 | 3.2 | 12.112 h |
| October | 31.2°C25.7°C | 25.7°C | 13 | 3.6 | 12.212 h |
| November | 30.9°C25.7°C | 25.7°C | 27 | 6.8 | 12.212 h |
| December | 30.4°C25.5°C | 25.5°C | 73 | 15.2 | 12.312 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
- São José de Ribamar in SeptemberBrazil · 27 kmHigh 30.1°C · Low 25.8°C · 11 mm rain
- Pinheiro in SeptemberBrazil · 87 kmHigh 32.0°C · Low 24.2°C · 14 mm rain
- Chapadinha in SeptemberBrazil · 171 kmHigh 34.9°C · Low 24.2°C · 3.5 mm rain
- Santa Inês in SeptemberBrazil · 174 kmHigh 34.0°C · Low 24.3°C · 12 mm rain
- Bacabal in SeptemberBrazil · 197 kmHigh 34.9°C · Low 24.7°C · 7.4 mm rain
- Codó in SeptemberBrazil · 219 kmHigh 35.2°C · Low 24.2°C · 6.2 mm rain
- Caxias in SeptemberBrazil · 279 kmHigh 36.1°C · Low 23.9°C · 5.0 mm rain
- Parnaíba in SeptemberBrazil · 284 kmHigh 33.8°C · Low 25.0°C · 1.1 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 São Luís) is explained once on the São Luís year overview and on the Sources, method and limits page.