Living in Wyoming isn't all beer and skittles, see an NBC News article reporting April snowfall in eastern Wyoming sufficient to close I-80. The blizzard dropped nearly 10 inches of snow in southeastern Wyoming.
The article doesn't mention Sherman Summit, between Cheyenne and Laramie on I-80. It climbs to 8640 feet, the highest pass on the transcontinental highway.
Locals claim it can snow any month of the year, perhaps true at the highest elevations. In 20 years I've not seen any in July and August, however June and September are another story.
