São Luís climate

Name: São Luís
Address: BR

São Luís is warmest in October, with average highs of 31 °C, and coldest in March, when nights average 24 °C. March is the wettest month (398 mm) and September the driest (13 mm). Figures are 1991–2020 climate normals.

Across a full year São Luís averages 1,861 mm of rain and 365 days above 25 °C.

Brazil · population 917,237 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month October 31 °C
Coldest month March 24 °C
Driest month September 13 mm
Wettest month March 398 mm
Least cloud August 33 % cloud
Hottest on record October 34 °C
Coldest on record August 22 °C
Warmest sea May 29 °C

What to expectSão Luís through the year

São Luís changes little through the year. Average daily highs stay between 28 and 31 °C, so no month stands out as a season in the way it would further from the equator.

Counted across a normal year, 365 days a year reach 25 °C, 153 of them reach 30 °C. The warmest reading in the 1991–2020 record is 34 °C, in October.

Rain is strongly seasonal. March averages 398 mm against 13 mm in September — 31 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off São Luís is warmest in May at 29 °C and coldest in October at 28 °C. Sea temperature lags the air by a month or two, which is why late summer swims warmer than early summer at the same air temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	29.1 °C	194 mm	77 %
February	28.4 °C	265 mm	82 %
March	28.2 °C	398 mm	86 %
April	28.4 °C	375 mm	85 %
May	28.9 °C	271 mm	70 %
June	29.2 °C	130 mm	50 %
July	29.4 °C	85 mm	41 %
August	30.6 °C	27 mm	33 %
September	31.2 °C	13 mm	34 %
October	31.2 °C	14 mm	42 %
November	31.0 °C	28 mm	55 %
December	30.5 °C	61 mm	63 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C
January	29.1 °C	24.7 °C	26.5 °C	33.5 °C	22.4 °C	31	7
February	28.4 °C	24.3 °C	26.0 °C	31.8 °C	22.3 °C	28	2
March	28.2 °C	24.2 °C	25.8 °C	31.7 °C	22.5 °C	31	1
April	28.4 °C	24.3 °C	25.9 °C	31.4 °C	22.6 °C	30	2
May	28.9 °C	24.6 °C	26.3 °C	31.8 °C	22.6 °C	31	3
June	29.2 °C	24.6 °C	26.5 °C	32.0 °C	22.8 °C	30	5
July	29.4 °C	24.6 °C	26.5 °C	32.4 °C	21.9 °C	31	7
August	30.6 °C	25.2 °C	27.2 °C	33.6 °C	21.8 °C	31	21
September	31.2 °C	25.4 °C	27.5 °C	34.3 °C	23.4 °C	30	27
October	31.2 °C	25.6 °C	27.6 °C	34.4 °C	23.7 °C	31	28
November	31.0 °C	25.7 °C	27.7 °C	33.9 °C	23.1 °C	30	27
December	30.5 °C	25.5 °C	27.5 °C	33.6 °C	22.6 °C	31	22

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	194 mm	24	12 h/day	77 %	82 %	17 km/h	28.1 °C
February	265 mm	26	12 h/day	82 %	85 %	16 km/h	28.3 °C
March	398 mm	30	12 h/day	86 %	87 %	15 km/h	28.4 °C
April	375 mm	29	12 h/day	85 %	87 %	14 km/h	28.7 °C
May	271 mm	27	12 h/day	70 %	86 %	14 km/h	28.8 °C
June	130 mm	21	12 h/day	50 %	83 %	14 km/h	28.8 °C
July	85 mm	17	12 h/day	41 %	80 %	15 km/h	28.4 °C
August	27 mm	8	12 h/day	33 %	75 %	18 km/h	28.1 °C
September	13 mm	3	12 h/day	34 %	73 %	22 km/h	27.6 °C
October	14 mm	3	12 h/day	42 %	73 %	22 km/h	27.5 °C
November	28 mm	5	12 h/day	55 %	74 %	21 km/h	27.7 °C
December	61 mm	12	12 h/day	63 %	76 %	20 km/h	27.9 °C

Where São Luís ranks

Ranking	Position	Value
The warmest places in South America in November	27thof 50	31 °C
The warmest places in South America in December	37thof 50	31 °C
The driest places in South America in October	45thof 50	14 mm
The warmest places in South America in October	48thof 50	31 °C
The driest places in South America in September	49thof 50	13 mm
The warmest places in South America in August	50thof 50	31 °C

Planning a trip? See the best time to visit São Luís.

QuestionsCommon questions about São Luís’s climate

When is the best time to visit São Luís?

That depends on what you want, so the honest answer is a comparison rather than a single month. February, March, April sit closest to 20 °C on average, October is the warmest month and September the driest. The month-by-month table above has the full picture.

How hot does São Luís get?

In October, the warmest month, daily highs average 31 °C. About 153 days a year pass 30 °C. The highest value in the 1991–2020 record is 34 °C.

How cold does it get in winter?

Nights average 24 °C in March, the coldest month. Freezing nights are not part of a normal year here.

Which month is wettest in São Luís?

March, averaging 398 mm over 30 days with rain. The driest month is September with 13 mm. The year as a whole averages 1,861 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in São Luís rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.