(Riverton, Wyo.) – Today, Friday, is the last official day of spring. Summer begins at 4:51 a.m. Saturday morning, mountain time, and tomorrow is officially the longest day of the year. The National Weather Service Forecast Office in Riverton produced a summer graphic to explain why it is the start of summer. See that above.  For a look at the weekend weather weather briefing, click on this link.

–National Weather Service, Riverton.