Castries month by month, at a glance
Hover each month for the summary. Click to pin it.
In 1999 Saint Lucia's carnival committee took a counterintuitive decision: to move it from February to July. The reason was commercial, not meteorological, and it is worth knowing before you book, because July has the most rainy days of the year.
01 There is no dry season here, only a less wet one
Castries has a tropical rainforest climate, and the figures confirm it: the city receives more than 1,800 millimetres of rain a year. Even the driest month, March, adds up to 66 millimetres over 11.7 rainy days.
In other words: in the year's best month it rains one day in three. What changes is not whether it will rain but how much falls and for how long. In March they are brief showers; in October, with 251 millimetres, they are entire afternoons.
Temperature, by contrast, is almost a constant: average highs between 29 degrees in January and 31.5 in September. Nobody travels here for the thermometer; you travel for how the rain is distributed.
Key moments at a glance
66 millimetres over 11.7 days, the year's minimum in volume.
11.1 rainy days, the best distribution on the calendar.
The month of the big festival and also of the most rainy days: 20.4.
250.9 millimetres, with hurricane season still open.
02 Why carnival moved to July
Until 1998 the carnival was held before Lent, as in most of the Caribbean. The problem was competition: coinciding with Trinidad's carnival meant losing musicians, audiences and international attention.
The move to July sought the opposite: a date of its own, without overlaps, coinciding with the northern hemisphere's summer holidays. It is a tourism-calendar decision, and it has worked.
What did not change was the weather. July accumulates 199 millimetres over 20.4 rainy days, the highest figure of the year. The festival goes ahead regardless, but you should expect rain on the parade.
03 Hurricane season takes up half the year
The Atlantic season runs from 1 June to 30 November and coincides almost exactly with the wet half of the year. August, September, October and November all exceed 200 millimetres a month.
In those months the practical problem is not the daily rain, which usually passes quickly, but the chance that a tropical system will close the airport or suspend boat departures for a couple of days.
In exchange, the island looks spectacular. With this rainfall regime the forest never rests, and in September and October the inland slopes are so green they seem to belong to another island.
04 A full calendar beyond carnival
July is not the only date circled. The last week of October brings Creole Day, with cooking, music and language events spread across the island's villages, and it is probably the most interesting moment of the year for anyone travelling for culture.
There are also two flower festivals with fixed dates, 30 August and 17 October, which set two traditional societies with more than two centuries of history against each other in friendly rivalry, celebrated mostly in rural communities.
And in January the city devotes several days to its two Nobel laureates, with lectures and events across Castries. It is a month of moderate rain and plenty of activity, and considerably less crowded than July.
Here the question is not whether it will rain, but on how many days and for how long.
05 How to choose
If you want the best weather, the window is February to April, with April the month of fewest rainy days and March the one with least accumulated rain. It is also when the sea is calmest for sailing between bays.
If you are coming for carnival, go in July and accept the deal: a big festival, expensive accommodation and twenty rainy days in the month. And if Creole culture interests you more than the parade, the last week of October gives you far more for considerably less.
