<%@LANGUAGE="JAVASCRIPT" CODEPAGE="1252"%> May and Spring 2010 Saint Cloud Weather Summary
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10 Warmest:
Marches Aprils

Very Warm Spring Despite Two Chilly Weeks

May and Spring 2010 Saint Cloud Weather Summaries

Fourth Warmest Spring in St. Cloud Records

Near-average May temperatures in St. Cloud could not prevent the meteorological spring (March 1-May 31) from being St. Cloud's 4th warmest spring out of the 130 years in St. Cloud temperature records. The spring average temperature of 48.6°F at the St. Cloud Regional Airport was 5.5°F warmer than the average and marked the warmest spring since 1987, in the midst of St. Cloud's last major drought and heat outbreak in 1986-1989. The warm spring was built mainly on the strength of St. Cloud's third warmest March and third warmest April (and the warmest April in 95 years). This combination produced St. Cloud's second warmest combined March and April, only falling short of March and April in 1910.

It did end up being the warmest spring on record in Duluth and the second warmest spring in International Falls.

Spring Warmth Comes In Spite of First Half of May

A fickle May 2010 could not prevent the near record warmth. May in St. Cloud produced an average temperature of 57.1°F, 0.6°F warmer than normal, but it was a tale of two seasons: a cold first two weeks more typical of April and the final 18 days with weather often typical of mid-summer.

During May 1-13, temperatures were very chilly with an average temperature of 46.9°F (high 55.6°F; low 38.1°F). These averages would be more typical of mid-April rather than May. There were 9 straight days with colder than normal temperatures, St. Cloud's longest streak since the first half of October of last fall. In the 13 days, there were only two days with a high of at least 60°F. This period also produced two frosts, including a hard freeze with a low of 26°F on May 9, more than a week later than the average date of the last 28°F low of April 30.

Part of this chilly weather included thunderstorms on the cold side of a front. During May 7-13, 1.92 inch of the total 2.06 May rainfall was produced. There were also snow flurries on May 7 and 8. The trace of snow on May 7 tied a record snow for the date and amounted to more snow that St. Cloud received in March and April combined. May 11's high of 44 degrees was only 4 degrees short of the record cold low for the date. We only got a few flurries, but northeastern Minnesota got as much as 4-6 inches of snow from that storm.

Fast Forward to Summer on May 14

However, the weather pattern dramatically changed on May 14 as St. Cloud finally emerged onto the warm side of the front. The May 14 high was 71 degrees; only the high on May 21 (70 degrees) was cooler for the rest of the month. During May 14-31, St. Cloud had an average temperature of 64.5°F (high 79.9°F; low 49.1°F), which would have ranked as the second warmest May on record if it had lasted for the whole month. Throwing out the first two weeks of May would have increased the spring average temperature to 51.1°F, the warmest spring by far.

90-Degree Highs, Including Warmest High Temperature in Nearly Three Years

There were 8 highs of at least 80°F in the last 18 days of the month and two highs of at least 90°F on May 24 and 29. On the average, St. Cloud has a 90-degree high every second year with 5 days in both 1900 and 1934 (the most). In the past 5 years, however, the May 90-degree highs have been coming a bit more frequently with 8 90-degree days, including 3 in 2006 and 2 in 2007. These Mays were the start of warm summers, especially in 2006, since we had 15 July days of 90 degrees or higher and our last 100-degree high on July 31. On the other hand, the high of 92 on May 20 last year was the warmest temperature of a cool summer with only two 90-degree highs.

In fact, this year's high temperature of 94°F on May 24 was the hottest temperature St. Cloud has seen since August 10, 2007, when the high temperature was 96°F. The 94 degrees on May 24 was one of four record high temperatures set on May 23 and 24.

Unprecedented Two 70-Degree Lows

The back-to-back mornings (May 23 and 24) with a 70-degree low is even more unusual. While St. Cloud averages 12 days with a high of at least 90 degrees over the average year, there are only 3 days on the average with a low of 70 degrees or warmer. In fact, there has only been one night that warm in the past three summers. And, when we get 70-degree lows, we don't get them often in May. There had been only 3 May days with a 70-degree low, one in 1898, one in 1939, and the most recent one on May 28, 2006 before May 2010. There has never been a May before with multiple 70-degree lows.

These warm lows are a real sign of mid-summer humidity since it takes either Florida-like humidity or noticeable humidity with a strong wind to produce lows that warm. Having a calendar day high of least 70 degrees also means that there can't be thunderstorms that night nor a front coming through before the following evening since a cooler air mass or thunderstorms would likely knock the low temperatures into the 60's or cooler before midnight the following night.

Cool Early May Weather Ends Trend of Early Spring Thresholds

The coolish early May weather delayed the first 80-degree high of the year to May 20, which is 16 days later than normal. All of the other spring thresholds were two weeks to a month early, as you can see by the table below. In fact, the March 14 high of 60 degrees was the 9th earliest in St. Cloud records.

St. Cloud Threshold 2010 Date Average (1896-2010) Rank
First 50-degree high March 14 March 26 51st earliest
First 60-degree high March 14 April 14 9th earliest
(record March 3, 1905)
First 70-degree high March 30 April 17 18th earliest
First 80-degree high May 20 May 4 20th latest
Last 32-degree low May 9 May 18  
Last 28-degree low May 9 April 30  

Tied for Fewest Frosts In A Cold Season

The May 9 low of 26 degrees was 9 days later than normal, but there were only two lows of freezing or colder in May. This means that there were 152 such days during the cold season of 2009-2010 with a low of freezing or colder. That ties 1899-1900 and 1924-1925 for the lowest number of sub-freezing days.

Dry Conditions Since Snow Melt Continued in May

Rainfall relieved some of the driest conditions in Minnesota during May, but the St. Cloud area lost ground. Total May rainfall was 2.06 inches, 0.91 inch below normal. The early month rain between May 7 and 13 (1.92 inch, 93% of the May total) helped to relieve the post-snowmelt dryness, as rainfall was 1.62 inch below normal from March 13 through May 6. However, St. Cloud missed nearly all of the rain from May 14 on, picking up only 0.09 inch, adding nearly another inch to the rain shortfall, as shown in the table below:

Period St. Cloud Precipitation Normal
March 13 through April 12 0.02 1.96
March 13 through May 6 1.54 3.16
Total since snowmelt through May 31 3.51 6.15
Spring (March 1-May 31) Precipitation 4.70 6.60

For the entire spring, there were 4.70 inches of precipitation, nearly two inches below the normal amount of 6.60 inches.

Depsite the lack of rain in St. Cloud from May 14 on, some parts of the state got a lot more rain. Strong storms hit northern Minnesota in the wake of the May 23-24 heat with large hail and a near-four-inch flash flood in Duluth. On the next day, flash flooding hit northwestern Minnesota with a swath of 4-5 inch rainfalls. Even during our rainy period, Onamia, Milaca, and Cambridge got a lot more rain than we did, so this week's Minnesota Climatology Working Group report on the dry spring shows rainfall within an inch of normal near Mille Lacs Lake, the St. Croix River, and the southwestern suburbs of the Twin Cities. The rainfall in northern Minnesota finally produced a little help for north central and northeastern Minnesota. As of June 1, however, the driest parts of Minnesota are in the southeast from Red Wing through Rochester to Fairmont, in the Upper Minnesota River valley near Benson and Montevideo, and from north central to northeastern Minnesota, especially in Lake and Cook Counties. The rainfall deficit in northeastern Minnesota is part of a Lake Superior basin dry spell that has lasted much of the past two growing seasons, producing moderate to severe drought, according to the National Drought Mitigation Center's Drought Monitor.

Still, the dry second half of May has led to a rainfall deficit over two inches in a swath from Glenwood through southern Stearns, southern Benton, and much of Sherburne counties.

No Spring Snow For Only Third Time

As noted earlier, St. Cloud had no measurable snowfall this spring. That's only the third spring in St. Cloud records without any measurable snow; the other two were in 1904 and 1905

 

    

 

May 2010 Statistics

 

 

 



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Last updated: 02-Jun-2010
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