Weather Trends in Castries, Saint LuciaWeather Trends in Castries,
Saint Lucia

Castries exhibits a warm tropical climate characterized by remarkable thermal stability throughout the year. WeatherBox data shows that the annual variation in daily mean temperature is merely 2.1°C (3.8°F), meaning conditions remain hot regardless of the season. Daily highs consistently reach an average of 30.1°C (86.2°F) during the warmest month. Nights provide limited cooling, with the lowest average monthly minimums only dropping to 23.8°C (74.8°F). While the heat is persistent, it is rarely extreme; temperatures seldom exceed 31.4°C (88.5°F).

Precipitation patterns drive the primary seasonal changes, shifting from a moderate dry season early in the year to a prolonged wet period. According to WeatherBox, the driest month sees an average rainfall of just 35 mm (1 in). In contrast, the wettest months—September through November—average 123 mm (5 in) of precipitation, peaking at 138 mm (5 in) in October. This rainfall accompanies intense humidity. Relative humidity reaches an average of 79.4 during the wettest intervals, and data indicates that "comfortable" humidity levels are recorded merely 0.3 of the time.

Solar energy remains high despite cloud cover variations. The city records substantial sunshine hours, ranging from a low of 265.7 to a high of 311.4 in March. The sun is intense, and the average peak UV Index is 11.6, necessitating year-round sun safety. Steady trade winds help moderate the muggy conditions, blowing from the E for 40.7 of the year. These winds are strongest in February, averaging 22.4 km/h (13.9 mph). Explore the advanced weather charts on WeatherBox for a deeper analysis of these climatic trends.