Castries, Saint Lucia Climate & Monthly Averages
The climate of Castries
Castries has one of the steadier climates in our dataset. Average highs move only 2°C across the whole year - from 81°F (27°C) in January to 86°F (30°C) in September - so the practical difference between seasons here is rainfall and daylight, not warmth.
Climate quick facts
- Hottest month: September - highs near 86°F (30°C)
- Coldest month: January - highs near 81°F (27°C)
- Decade extremes (2015-2024): 91°F (33°C) high · 67°F (19°C) low
- Wettest month: July (24 rainy days) · Sunniest: April (11.8 h sun/day)
- Climate type: tropical wet-and-dry
- Annual swing: 2°C between the average warmest and coolest month · day to night: 5°C
- Months averaging 30°C or hotter: 1
- Average humidity: 77%
Temperatures through the year
At its warmest, in September, Castries runs to 86°F (30°C) in the afternoon and back to 77°F (25°C) by dawn. January sits at the other end of the year: 81°F (27°C) by day, 73°F (23°C) at night. Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 91°F (33°C) and the lowest daily minimum 67°F (19°C). Sunshine averages 11.2 hours a day over the year - sunnier than almost anywhere else we cover, peaking in April at 11.8 hours.
Rain, sun and snow
Days and nights are about 5°C apart on average - narrower than almost anywhere else we cover. July is the wettest month at 4.6 inches (116 mm) over 24 days; April is the driest. Between the average September and the average January lie 2°C, a narrower spread than all but 6% of the 3496 cities in our dataset.
How Castries compares
- Rain or snow reaches the ground on 216 days a year - more wet days than 93% of the 3496 cities we track.
Ranked against every city in our dataset, each measured on the same ten-year window.
Monthly climate table
| Month | High | Low | Rain days | Precipitation | Sunshine | Daylight | Wet-day chance | Humidity |
|---|---|---|---|---|---|---|---|---|
| January | 81° | 73° | 18 | 2.2 in | 10.8 h/day | 11.4 h | 57% | 76% |
| February | 81° | 73° | 13 | 1.8 in | 11.1 h/day | 11.7 h | 45% | 74% |
| March | 82° | 73° | 15 | 1.9 in | 11.6 h/day | 12.0 h | 49% | 74% |
| April | 84° | 74° | 12 | 1.5 in | 11.8 h/day | 12.4 h | 41% | 73% |
| May | 85° | 76° | 13 | 1.9 in | 11.7 h/day | 12.8 h | 41% | 74% |
| June | 85° | 76° | 19 | 3.3 in | 11.3 h/day | 12.9 h | 63% | 77% |
| July | 84° | 76° | 24 | 4.6 in | 11.5 h/day | 12.9 h | 78% | 80% |
| August | 85° | 76° | 23 | 4.2 in | 11.3 h/day | 12.6 h | 73% | 80% |
| September | 86° | 77° | 22 | 4.5 in | 11.2 h/day | 12.2 h | 72% | 80% |
| October | 85° | 76° | 21 | 3.9 in | 10.8 h/day | 11.8 h | 67% | 80% |
| November | 83° | 75° | 21 | 4.4 in | 10.5 h/day | 11.5 h | 69% | 80% |
| December | 82° | 74° | 17 | 2.2 in | 10.7 h/day | 11.3 h | 55% | 77% |
Castries month by month
Average high and low for each month, with the bar showing where it sits in Castries's year (left is the coldest night, right is the warmest afternoon).
January
- Rain
- 18 days
- Sunshine
- 10.8 h
- Daylight
- 11.4 h
February
- Rain
- 13 days
- Sunshine
- 11.1 h
- Daylight
- 11.7 h
March
- Rain
- 15 days
- Sunshine
- 11.6 h
- Daylight
- 12.0 h
April
- Rain
- 12 days
- Sunshine
- 11.8 h
- Daylight
- 12.4 h
May
- Rain
- 13 days
- Sunshine
- 11.7 h
- Daylight
- 12.8 h
June
- Rain
- 19 days
- Sunshine
- 11.3 h
- Daylight
- 12.9 h
July
- Rain
- 24 days
- Sunshine
- 11.5 h
- Daylight
- 12.9 h
August
- Rain
- 23 days
- Sunshine
- 11.3 h
- Daylight
- 12.6 h
September
- Rain
- 22 days
- Sunshine
- 11.2 h
- Daylight
- 12.2 h
October
- Rain
- 21 days
- Sunshine
- 10.8 h
- Daylight
- 11.8 h
November
- Rain
- 21 days
- Sunshine
- 10.5 h
- Daylight
- 11.5 h
December
- Rain
- 17 days
- Sunshine
- 10.7 h
- Daylight
- 11.3 h
Warmer places to go, by month: January · February · March · April · May · June · July · August · September · October · November · December
Seasons in Castries
March through May
Through March through May, Castries sits firmly in the heat: 84°F (29°C) by day, 74°F (24°C) after dark, and rain falls on around 40 of the 90 days. Daylight is generous - around 11.7 hours of sun a day. With the moisture factored in, afternoons feel hotter than the reading suggests - the humidity and dew point converter shows why.
June through August
June through August is hot here - highs near 84°F (29°C), nights near 76°F (25°C), and rain falls on around 66 of the 90 days. Daylight is generous - around 11.4 hours of sun a day.
September through November
Through September through November, Castries sits firmly in the heat: 85°F (29°C) by day, 76°F (25°C) after dark, and rain falls on around 63 of the 90 days. Daylight is generous - around 10.8 hours of sun a day.
December through February
December through February in Castries sits firmly in the heat, with daytime highs averaging 81°F (27°C) and nights around 73°F (23°C); rain falls on around 47 of the 90 days. Daylight is generous - around 10.9 hours of sun a day.
Climate questions, answered
How cold does Castries get in winter?
How hot does Castries get in summer?
How does Castries compare to other cities?
How much do temperatures drop at night in Castries?
Best time to visit Castries
Aim for January to April and July if you get the choice: humidity and rainfall are at their lowest, which is what actually varies here, and highs average 83°F (28°C) against roughly 17 wet days a month. For the same question asked the other way round, see where else is warm in January.
Pack for Castries with light clothing for the warm months, proper waterproofs rather than an umbrella - wet days are the norm here and moisture-wicking fabrics for the humidity. Note the gap between afternoon and night: September pairs 86°F (30°C) with 77°F (25°C).
Castries temperature records (2015-2024)
Derived from ERA5 reanalysis data, 2015–2024. Official station records may differ. Need the precipitation in other units? The mm-to-inches rainfall converter handles it.