Summer
Dates: June - August
Weather: Temperatures vary throughout the summer. On average summer nights are almost always cool, temperatures ranging in the 40s, but getting considerably chilly in mountain locations. Daytime temperatures recover drastically from 70 to 90 degrees Fahrenheit. You can expect clouds to appear around noon and by mid-afternoon you may see scattered thundershowers.
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Fall
Dates: September - October
Weather: Autumn in Wyoming is a delight. Many locations will see snow in mid-September, but it doesn’t get to be real winter until late November. During October and November you’ll discover a warm Indian Summer, with cool nights and beautiful changing colors. Early freezes in the fall are common.
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Winter
Dates: November - March
Weather: Winters in Wyoming are usually long and cold. January is usually the coldest month of the year. At this time, the minimum temperatures are between 5 and 10 degrees. There are some mild periods when it gets up to the 50s. It gets colder in the western valleys – usually 5 degrees below zero. Snow falls often from November through March. Winter is a great time to visit Wyoming if you enjoy winter sports.
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Spring
Dates: April - May
Weather:
As the warm weather approaches, the flowers start to bloom, but early freezes and late winters are characteristic of spring in Wyoming. Always carry warm clothes and prepare for snow. Many locals leave during this time of year to escape the melt and you may find that businesses have limited hours.
Things to Do:
For outdoor adventures, it's good to come prepared in Jackson year-round for any adventure. It has famously snowed on Independence Day in Jackson Hole during the fireworks. Pack layers, as it can be hot and cold in the same day during the summer.
Around town, almost anything goes. Even the millionaires in Jackson tend to dress down for their time on the town. Denim pants or athletic wear are commonly seen, as is high-end Western chic apparel. Very few restauarants have a dress code, and even fewer enforce one. Even the most high-end restauarants call for "Jackson casual" or "dressy casual" wear, with the former translatable to nearly anything you want to wear.
Jackson Hole boasts year-round outdoor activities, but the options really open up in summer, fall, and winter.
In summer, visitors love the hiking, whitewater rafting, wildlife viewing, and access to the Tetons and Yellowstone.
In fall, you'll find that the crowds have died down and chill morning air is balanced by a radiant sun that still allows for deep access to the mountains. Wildlife is also in peak form going into fall, leading to numerous viewing opportunities.
Winter offers skiers, snowboarders, snowmobilers and other winter enthusiasts to play to their hearts' content. Jackson Hole Mountain Resort, Grand Targhee Resort and Snow King Mountain offern plenty of skiing options close to town.
Spring tends to be the quietest time of year in Jackson, largely because of iffy weather that can swing between bluebird spring days and dead-of-winter storms - sometimes in the same day. Spring skiing both at the resorts and in the backcountry can continue to be phenomenal, though avalanche danger can be high.