The climate in Sint Maarten is tropical, hot and sunny all year round: the daily average temperature goes from 25 degrees Celsius (77 °F) in the period from January to March, to 28 °C (82 °F) from June to October. The night temperature rarely drops below 20 °C (68 °F), while sometimes it can touch 35/37 °C (95/99 °F) during the day, from June to November. In the hottest period there's a muggy heat, though the breeze relieves it a little.
Here are the average temperatures of the capital Philipsburg.
Average temperatures - Philipsburg

Philipsburg	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Philipsburg	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	22	22	23	23	24	25	25	25	26	25	24	23
Max (°C)	28	27	28	28	29	30	30	31	31	30	29	28
Min (°F)	72	72	73	73	75	77	77	77	79	77	75	73
Max (°F)	82	81	82	82	84	86	86	88	88	86	84	82

Sint Maarten is an island of the Lesser Antilles, located at a latitude of 18 ° north, and is administratively divided between France and the Netherlands; here we are dealing with the Dutch side, located in the south.
Normally the rainfall is not abundant, since the annual average amounts to around 1,000 millimetres (40 inches); February and March are the least rainy months, with about 45/50 mm (1.8/2 in) per month, while the rainiest period runs from August to November.
Here is the average precipitation.
Average precipitation - Philipsburg

Philipsburg	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Philipsburg	J	F	M	A	M	J	J	A	S	O	N	D	Y
Prec. (mm)	75	50	45	80	100	70	85	115	120	100	115	90	1045
Prec.(in)	3	2	1.8	3.1	3.9	2.8	3.3	4.5	4.7	3.9	4.5	3.5	41.1
Days	10	8	7	8	10	8	9	12	13	12	13	12	122

However, the rains come in the form of downpour or thunderstorm, which do not last long, so that the sun can shine throughout the year, as can be seen in the following table.
Sunshine - Philipsburg

Philipsburg	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Philipsburg	J	F	M	A	M	J	J	A	S	O	N	D
Sun (hours)	8	8	9	9	8	8	8	9	8	8	8	8

In the period from June to November (but mostly from August to October), Sint Maarten can be hit by tropical depressions and hurricanes, as happens in general in the Caribbean.



In Sint Maarten, the sea is warm enough for swimming all year round, even though it is a bit warmer in the summer months, as we can see from the following table.
Sea temperature - Sint Maarten

Sint Maarten	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sint Maarten	J	F	M	A	M	J	J	A	S	O	N	D
Sea (°C)	26	26	26	26	27	28	28	28	29	29	28	27
Sea (°F)	79	79	79	79	81	82	82	82	84	84	82	81

The best time to visit the island where Sint Maarten is located goes from December to April, being the least hot and outside the hurricane season, in particular the period from February to March is usually the least rainy. In May, both temperature and moisture increase, but the rains are not yet too abundant, and we are still out of the hurricane season. In summer, June and July are less rainy than August and September, besides tropical storms and hurricanes are less likely to occur than in the following months.


All year round: light clothes of natural fabric, possibly a light sweatshirt and a light raincoat for thunderstorms, especially from August to November; a light sweatshirt for the evening from December to March.
For the reef, equipment for snorkeling, water shoes or rubber soled shoes.