A dusting of freshly fallen snow covered parts of the forest floor near the summit of Mount Lemmon on Monday, May 20.

Snow falling on Lemmon, the 9,157-foot high point of the Catalina Mountains, is almost unheard of at this time of year when temperatures sometimes top 100 degrees in Tucson.

Elsewhere in the Catalinas on Monday, saguaro cacti and wildflowers were blooming.

The snow came in a period of unusually cool weather for May in Southern Arizona.

Temperatures in the city Monday were in the 60s and low 70s instead of the 90s, as is often the case.

The snow that fluttered down, rapidly at times, on Mount Lemmon stuck on the forest floor and on tables at a picnic area.

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But don’t break out the sleds or cross-country skis. It’s just a bit of snow, and it’s highly unlikely that it will last long.

Snow in May might be almost unheard of, but not completely.

“It’s rare, but it can happen,” said John Glueck, a meteorologist with the National Weather Service.

Glueck said records show that 1.8 inches of snow fell at Mount Lemmon Ski Valley in the Catalinas on May 21, 1992 — 27 years ago.

Contact reporter Doug Kreutz at dkreutz@tucson.com or at 573-4192. On Twitter: