Fire Island National Seashore's weather can vary widely between the island and the mainland of Long Island. Historically, seasonal temperatures have ranged from below zero during December, January, February, and March to over 100º in August. Average temperatures in this maritime climate are much more moderate, however.
The fall and winter months along the coast are relatively cool and dry, with brief periods of rain. Spring along the coast can be cool and windy. Summers on Fire Island are typically warm and humid.
Annual precipitation averages 38.9" with the distribution being relatively consistent throughout the year.
Global climate change is one of the critical natural resource issues that concerns the National Park Service.
At Fire Island National Seashore, the major repercussion of changing temperatures lies in sea-level rise. The National Park Service and the United States Geological Survey are currently developing Coastal Vulnerability Index (CVI) maps for coastal parks to identify coastal areas sensitive to sea-level rise.