The weather in the Grand Teton National Park runs encompasses the whole spectrum of temperatures and conditions throughout a year. The contrast between summer and winter weathers is remarkable.
The Jackson Hole area is famous for long, harsh winters and equally trying summers. Heavy snow fall starts with November and continues well into April. However, snow and frost should be expected anytime of the year really; snow storms come hard and fast to the Grand Teton National Park.
From April to June, the weather remains mild. You will find the trails to be covered with snow from Mid April to May, with sporadic showers and snowing to make your hikes more exciting.
July and August are when the days are warm, but afternoon thundershowers commonly turn the nights quite cold.
September, October and November in the Grand Tetons are a sunny affair. The days are nice and sunny, but the nights may get cold because of occasional snow storms and rains.
The weather from December through to Mid April is perfect for snow enthusiasts as the mountains and valley are all covered with a blanket of white. However, visitors are advised to travel the park in all-wheel drives because snow may get extreme at some points. Recurring blizzards often close up roads, trails and paths, and it is a good idea to visit the nearest ranger office for weather updates before heading out for a hike.