5:30 AM MDT, Friday, May 24, 2019
Sunny weather and warmer temperatures return today after an unusually persistent cool spell for this time of year. The weekend looks springlike too. I can’t completely rule out a stray shower Saturday or Sunday, but most areas are likely to stay dry with mainly sunny skies and low elevation temperatures in the 70s.
Monday will probably continue the mainly sunny and dry weather, but that day is a little more questionable. The next change to cooler and more showery weather will probably arrive Monday evening, but the timing is still a bit uncertain.
Where the recent cool snap ranks historically
The following statistics are for the Boulder climate station. There was one record low maximum (43 on May 21st), and we tied one record low minimum (32 on May 22nd). But the most notable aspect of the cool snap was the number of consecutive days that failed to reach 50 degrees. Since 1897 there have been four times when a cool snap in May kept the temperatures below 50 for 4 consecutive days: 1897, 1907, 1917, and 1920 (in 1907 it was 5 consecutive days). This year we had 4 consecutive days below 50 from May 20-23rd. It was the first time for such an occurrence in 99 years and the only time at the current climate station location (established in 1990). But what is even more notable is that the previous four May cool snaps ended on or before May 16th. So this year had the latest occurrence of such a stretch of cold days.