weather in sanibel island
Sanibel Island weather essentials. Sanibel can be enjoyed all year round. Mid-December through mid-February are the coldest months, and June thru the end of November are hurricane season. Sanibel rarely see long spells of cold weather. Officially, Key West is the only 'frost free' location in the continental US, but sitting in the warm Gulf, Sanibel and Captiva are nearly as mild.