Climate Overview
The climate in São Sebastião do Caí is warm and mild. The average annual temperature is 19°C and approximately 1800mm of precipitation falls per year. São Sebastião do Caí receives a notable amount of rainfall throughout the year, including during its driest month. São Sebastião do Caí is in the Southern Hemisphere. The seasons are reversed — summer runs from December to February, while winter falls between June and August. The summer months are: January, February, December. The coldest months are July, June, August, when temperatures can drop to 10°C.
Temperature
São Sebastião do Caí sees moderate temperature variation throughout the year, ranging from 10°C to 29°C. The warmest month is January, when average highs reach 29°C and the mean temperature sits around 24°C. July is the coolest month, with minimum temperatures around 10°C and an average of 14°C. On average, daily temperatures fluctuate by about 10°C between overnight lows and afternoon highs. The sharpest temperature change occurs between April and May, with a 4°C shift in average temperatures.
Precipitation
São Sebastião do Caí is a fairly wet location, receiving approximately 1800mm of precipitation annually, which averages out to around 150mm per month. The wettest month is October, averaging 184mm of rainfall. January and September also tend to see above-average precipitation. The driest month is August, with just 116mm. That's 68mm less than October, the wettest month. Rainfall is relatively evenly distributed throughout the year, so there is no pronounced dry or wet season to plan around.
Wind
São Sebastião do Caí is relatively calm, with an average annual wind speed of 2km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is October, averaging 2km/h, though still comfortable for most outdoor activities. The calmest conditions occur in February, with average winds dropping to 2km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 0km/h between the calmest and windiest months.
Seasons
93 days until Spring
It is currently winter in São Sebastião do Caí, which began on June 21, 2026. São Sebastião do Caí is in the Southern Hemisphere, where the seasons are reversed — spring starts in September, summer in December, autumn in March, and winter in June. The warmest period peaks in January at around 29°C, while the coldest stretch bottoms out in July near 10°C. Spring is next, beginning on September 23, 2026 — 93 days from now.
Spring
Temperatures range from 13 to 26°C. Rainfall is heavy, totalling around 508mm across the season with a monthly average of 169mm. Winds are generally light, averaging 2km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.
Summer
Temperatures range from 18 to 29°C. Rainfall is heavy, totalling around 460mm across the season with a monthly average of 153mm. Winds are generally light, averaging 2km/h. Light, breathable clothing is ideal — perfect conditions for outdoor activities.
Autumn
Temperatures range from 13 to 27°C. Rainfall is heavy, totalling around 460mm across the season with a monthly average of 153mm. Winds are generally light, averaging 2km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.
Winter
Temperatures range from 10 to 21°C. Rainfall is heavy, totalling around 372mm across the season with a monthly average of 124mm. Winds are generally light, averaging 2km/h. A light jacket or sweater is usually sufficient, though cooler evenings may call for an extra layer.
Monthly Climate Data
The table below shows monthly climate averages for São Sebastião do Caí based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.
