The weather across Katmai can vary considerably during the course of a single day from heavy rain, to cold winds, to warm sun, and back to heavy rain. Summer temperatures range from upper 30s to low 80s and almost constant winds. Visitors to the park should be prepared for all types of weather. 

Summers in Katmai are cool with frequent high winds and rain. Please note that following heavy rainstorms, most rivers in Katmai rise quickly and become extremely hazardous to cross. Insects can be intense and headnets are recommended.

Winter in Katmai means cold, quiet, and beauty. Temperatures can range from -40F to 40F with snow or rain possible throughout the season. Generally all bodies of water are frozen with snow covering the high elevations until spring.