Weather in St Lucia in August

How August compares

August is the 4th warmest month of the year in St Lucia and ranks 63rd of 134 destinations we compare for August - see where else is hot in August. Against London's average high of 21.4°C in August, St Lucia is 7.6°C warmer by day and 11.6°C warmer at night.

Daytime and night-time in August

The typical August day in St Lucia peaks at 29.0°C, but that is an average: the warmest 10% of days reach 30.0°C or more. About 100% of days top 25°C and 1 in 9 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 August day here reached 31.4°C (1996-08-30) and the coldest night 23.0°C (2017-08-10).

Rain in August

Wet (more than 8 rainy days): about 21 days with 1 mm or more, 101 mm in total. Year to year it varies a lot - the wettest August was 2007 with 189 mm, the driest 1991 with 52 mm. Humidity averages 79%, which makes the heat feel heavier than the thermometer suggests.

Sea temperature in August

The sea averages 28.6°C - warm enough to swim (22°c+). Depending on the year it ranges from 28.1°C to 29.1°C. For the warmest sea here, come in September (29.0°C).

Sunshine and daylight

Around 5.6 hours of sunshine a day (estimated from cloud cover), 12.5 hours of daylight: the sun rises about 05:51 and sets about 18:26 local time in mid-August. Average cloud cover is 55%.

Is August a good time to visit St Lucia?

It is a reasonable choice: hot days but expect showers. The best months for St Lucia on our scoring are February, March, January; months averaging 25°C or more: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec.

Hot days, with little cooling after dark

The heat is consistent rather than extreme: days reaching 30°C account for 11% of August, but the average daytime high is still 7.6°C above London's. Humidity of 79% adds to the sense of warmth, so loose, light clothing and an unhurried pace are sensible. Keep strenuous outdoor plans away from midday where possible, and leave room for shade breaks. Evenings offer limited relief, with average lows around 25°C, so do not expect the cool finish to the day you might get at home. If you struggle to sleep in warm rooms, prioritise accommodation with effective cooling rather than relying on the night air.

Plan around rain, not uninterrupted sunshine

August is wet, so flexibility matters more than a tightly packed outdoor schedule. About 21 days receive measurable rain, although that does not mean those days are complete washouts. There are around 5.6 hours of sunshine within 12.5 hours of daylight, leaving plenty of time when sunshine is not guaranteed. Carry a light waterproof and keep belongings protected from rain, but avoid heavy layers that will feel uncomfortable in the humidity. Rather than assuming mornings or afternoons will be dry, let the day's weather guide your plans. August is a reasonable fit if you can shift activities around; it is less suitable if rain interruptions would spoil the holiday.