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São Luís weather by month
Historical averages 2016–2025 · not a forecast
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When is the best time to visit São Luís?
For a warm holiday, the best week has been 21–27 September (Weather Index 91). Favourable start dates for a 7-day trip run from 8 September to 29 October. September, October and November are warmest (31°C), September is driest and July to October have the most sun.
- Warmest
- September, October and November 31°C
- Coolest
- January to April 29°C
- Driest
- September 6% rain-day chance
- Wettest
- April 98% rain-day chance
- Sunniest
- July to October 12 hours a day
A rain day has 1 mm or more, snow included, so a short shower counts. Monthly averages below give the amounts.
Monthly averages in São Luís
São Luís historical monthly estimates, 2016–2025. Temperatures and sunshine are daily averages.
| Month | High (°C) | Low (°C) | Rain-day chance (%) | Expected rain days | Precipitation (mm/month) | Sunshine (hours/day) |
|---|---|---|---|---|---|---|
| January | 29.3 | 24.8 | 85.8 | 26.6 | 215.0 | 10.0 |
| February | 28.9 | 24.6 | 93.9 | 26.3 | 316.7 | 9.0 |
| March | 28.8 | 24.6 | 96.5 | 29.9 | 436.5 | 8.6 |
| April | 29.1 | 24.8 | 97.7 | 29.3 | 424.6 | 9.1 |
| May | 29.6 | 25.2 | 80.3 | 24.9 | 229.4 | 10.5 |
| June | 29.5 | 25.1 | 66.3 | 19.9 | 115.5 | 11.3 |
| July | 29.7 | 24.9 | 49.7 | 15.4 | 66.8 | 11.6 |
| August | 30.5 | 25.3 | 21.6 | 6.7 | 23.1 | 11.9 |
| September | 30.7 | 25.6 | 6.3 | 1.9 | 10.6 | 11.9 |
| October | 30.8 | 25.8 | 9.4 | 2.9 | 12.4 | 11.7 |
| November | 30.6 | 25.7 | 20.7 | 6.2 | 36.6 | 11.4 |
| December | 30.3 | 25.6 | 54.5 | 16.9 | 83.5 | 10.9 |
Each month averages its own days. Precipitation includes snow. About the data
Sources
Open-Meteo · 1 Jan 2016 – 31 Dec 2025
- Open-Meteo Historical Weather API
- Local days, 2016–2025, every year weighted equally. Each weekly chart averages its own seven days, without smoothing.
- Shading shows the 10th–90th percentile of past days, not forecast confidence.
- A rain day has at least 1 mm, snow included. The last weekly period has eight days.
- Wind is the average daytime (10:00–18:00) maximum, not gusts. Daylight is calculated from latitude. Missing readings stay blank.
- Mugginess (dew point) comes from the original daily summaries, on UTC days.
- The live two-week forecast comes from the Open-Meteo Weather Forecast API. The Weather Index does not use it.