Climate - Saint Kitts And Nevis. Temperature, rainfall, prevailing weather conditions, when to go, what to pack. The climate in St. Kitts and Nevis is tropical, hot and humid all year round. Saint Kitts and Nevis is a state of the Lesser Antilles, formed by two islands of the same name, and the capital city is Basseterre. The daily average temperature is around 25 degrees Celsius (77 Â°F) in January and February, and 28 Â°C (82 Â°F) from June to October, which is the hottest period. Sea breezes temper the heat in the summer months, which however is definitely muggy.