Castries, Saint Lucia Climate & Monthly Averages
Castries has a tropical wet-and-dry climate. September is the hottest month, averaging 86° by day; January is the coldest at 81°.
Rain, not cold, divides the year in 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.
The wet-and-dry rhythm at a glance
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.
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.
More climate facts for Castries
- 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%
Choosing the right part of the year in Castries
Choose dates by rain, not just temperature
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.
What the humidity changes
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).
Warm all year: the monthly rain pattern
Each card shows the average high and low. The bar places that month between Castries's coldest night and 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
Looking for warmer alternatives? Browse warm places by month, or compare Castries's coolest part of the year: January, February, December.
Monthly temperature and rain 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% |
How Castries compares for rain and warmth
- Rain or snow reaches the ground on 216 days a year - more wet days than 93% of the 3496 cities we track.
These comparisons use the same ten-year window for every city in the dataset.
How the calendar changes in warm-weather 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.
Questions about heat and rain in Castries
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?
Castries temperature extremes in the 2015–2024 dataset
Derived from ERA5 reanalysis data, 2015–2024. Official station records may differ. Need another precipitation unit? Use the rainfall converter.