May and Spring 2023 Saint Cloud Weather Summary

When Will Summer Finally Arrive? May Proved You Can Stop Asking

May and Spring 2023 Saint Cloud Weather Summaries

I could hear you groaning all of February, March, and April while digging out the last chunks of our record snowfall season. I could hear even more when our perpetual early March temperatures remain early-March-like, even through late March and all of April. But, on May 3, the temperatures finally returned to the 70's. On May 11, St. Cloud had only its second 80-degree high and the first in 28 days. This shift turned the tide, as high temperatures were more consistently in the 70's and broke 80 on 9 of the last 11 days. On May 31, the high hit 90 (91 degrees) for the first time this summer and with 3 more 90-degree days in the first 4 days of June.

That warm-up pushed St. Cloud's average May temperature to 62.5 degrees, 6.3 degrees above normal. That's the 9th warmest May in St. Cloud records. That warmth also brought an end to the high precipitation trend of 2023's first four months dry; only 0.87 inch fell in May, 2.79 inches below average and ranking as the 4th driest May in St. Cloud records. That's a complete reversal from the 9th wettest January-April (9.97 inches, 4.36 inches above average) and the 28th coldest March-April combination (4.0 degrees colder than average).

The turn-around came, despite the double storm track seen so frequently across the US during the cold season. This time, however, the northern branch of the steering winds over Canada often ground to a halt with a stalled low in eastern Canada or the Northeastern US and a strong high somewhere between the Intermountain Region and the Great Lakes. The combination of the high and the northwest-to-southeast steering winds along the eastern side of the high kept air mainly sinking, both down the eastern slopes of the Rockies, and over the Canadian Prairie Provinces. That warmed up the air, even far to the north in Alberta and Saskatchewan, meaning there was plenty of warm air to bring into Minnesota. This flow made it hard for Gulf of Mexico high moisture air to make it this far northward. It usually only made it through the High Plains and into Iowa (see red areas, meaning more than 5 May inches on the NWS Continental US rainfall chart). There was one heavy rain storm in southern Minnesota during the middle of the month (see Southern Minnesota Flooding May 10-14), but most of central and northern Minnesota got missed (see NWS Minnesota May rainfall chart). That led to periodic high to extreme fire danger in northern and western Minnesota during the month.

The other major weather-related issue during May in Minnesota was the frequent smoke from the various wildfires, both in northern Alberta and Saskatchewan and in Quebec. The cold season weather pattern that produced so much snow in the northern and mountain US (set to season accumulation on the NWS NOHRSC Continental US snowfall analysis) left much of Canada high and dry, so the warm weather triggered several early wildfires in the past two months. Flow from the Canadian Prairies often blew the smoke aloft into the northern US, making skies hazy. At times, sinking of the air wrapping around the stalled high allowed the smoke plume to drop to the ground, creating outbreaks of serious pollution in Minnesota. The worst outbreak was named by the Minnesota Department of Natural Resources climatology department a "smoke front" on May 18.

St. Cloud got through May frost-free. There was one close call (low of 33 degrees on May 3), In this case, the wet ground helped to moisten the drier air (originally with dew points in the 20's) enough to avoid a frost. So, the apparent last frost came on April 26, two weeks earlier than average (see below). While that was going on, May's warmth helped to kick-start the degree days totals for the growing season after the slow start due to the spring cold and wetness.

The dry May has actually offset much of the wet start to the year. For the growing season, usually thought of as from April on, St. Cloud is now 1.66 inches behind (total: 4.61 inches; average 6.27 inches). Even the 2023 running total of 10.84 inches is only 1.54 inches above the average of 9.27 inches. From a ground water standpoint, we were fortunate that some of the snow melt crept into the ground. However, the winter months are the worst months to be way ahead on precipitation, since these are the driest months of the year. That's because warm air can hold a lot more water vapor than cold air (ability of the air to store water vapor roughly doubles for every 18 degree increase in the normal range of temperatures). This has nothing to do with the precipitation being snow and being piled high in our faces this season. So, this dry May cost 2.79 inches of the 4.32 inches we were ahead of the annual total. That's also why the grass is brown, and some of Minnesota is listed as being short on precipitation (see latest US Drought Monitor).

St. Cloud's average temperature was for meteorological spring (March 1 through May 31) is 44.8 degrees, 1.9 degrees above average.

There was no snowfall in May (seriously!), but that still meant 27.9 inches during the meteorological spring, mostly fueled by March's 23.5 inches (4th snowiest March). That's the 9th snowiest spring on record