Weather in Boa Vista in September

How September compares

September is the 1st warmest month of the year in Boa Vista and ranks 25th of 134 destinations we compare for September - see where else is hot in September. Within Cape Verde it is 1st of 2 (Cape Verde in September). Against London's average high of 18.6°C in September, Boa Vista is 10.8°C warmer by day and 13.9°C warmer at night.

Daytime and night-time in September

The typical September day in Boa Vista peaks at 29.4°C, but that is an average: the warmest 10% of days reach 30.8°C or more. About 100% of days top 25°C and 1 in 3 pass 30°C. Nights average 25.1°C; one night in ten drops to 24.2°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest September day here reached 32.4°C (2006-09-12) and the coldest night 22.5°C (1994-09-22).

Rain in September

Some rain (4-8 rainy days): about 6 days with 1 mm or more, 37 mm in total. Year to year it varies a lot - the wettest September was 2010 with 110 mm, the driest 2017 with 2 mm. Humidity averages 77%, which makes the heat feel heavier than the thermometer suggests.

Sea temperature in September

The sea averages 26.6°C - warm enough to swim (22°c+). Depending on the year it ranges from 26.0°C to 27.2°C. This is the warmest the sea gets here all year.

Sunshine and daylight

Around 6.3 hours of sunshine a day (estimated from cloud cover), 12.1 hours of daylight: the sun rises about 06:20 and sets about 18:34 local time in mid-September. Average cloud cover is 48%.

Is September a good time to visit Boa Vista?

Yes - it is one of the better months: hot days, manageable rain. The best months for Boa Vista on our scoring are June, May, March; months averaging 25°C or more: Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec.

Expect heat that lasts into the evening

Boa Vista feels substantially hotter than London in September, with average daytime highs 10.8°C higher. Around 31% of days reach 30°C, so plan more active outings for the morning or later afternoon rather than the middle of the day. Humidity averages 77%, which can make the warmth feel sticky, particularly when you are moving about. Loose, breathable clothing is more useful than heavy layers, and accommodation with air conditioning is worth prioritising if warm bedrooms disturb your sleep. Evenings offer limited relief: average lows remain around 25°C. This suits travellers who enjoy sustained heat, but it is not the month to choose for crisp nights or comfortable midday exertion.

Allow for rain and time out of the sun

September brings about 6 rainy days, so leave some flexibility in plans that depend on dry weather. That does not mean the whole month is wet, but a completely rain-free stay is not something to count on. Sunshine averages about 6.3 hours within 12.1 hours of daylight, so long days do not translate into continuous clear skies. A light waterproof layer is sensible, though heavy rainwear could feel uncomfortable in the humidity. Keep sun protection handy rather than treating cloud cover as a reason to leave it behind. September works best if you are happy to adjust your day around the weather, rather than expecting uninterrupted sunshine throughout your stay.