Overview: Gros IsletGros Islet (Saint Lucia) in general has a tropical climate. Temperatures during the day are in the range from 29 °C (85 °F) in January to 32 °C (89 °F) in September. Temperatures during the night go from 22 °C (72 °F) in February to 24 °C (76 °F) in July. The driest month is March with just 13 days of rain, on the contrary, the month when it rains the most is November with 21 days of rain. Sea temperatures are in the following range: 26 °C (80 °F) in February to 29 °C (84 °F) in September.