Not Quite Extreme, But Persistent Heat Dominated July

St. Cloud July 2012 Weather Summary

The persistent heat and drought has dominated the news across the US this spring and summer. The extreme heat also helped to produce the second hottest July and the second warmest temperature of any month in the Twin Cities. While it has been hot in central and northern Minnesota, it hasn't been near record-breaking as often as it has been to the south.

The St. Cloud average July temperature has been 76.5°F, a whopping 6.1°F warmer than normal, and the warmest July since 1936 (6th warmest overall). It was also the 13th straight month of an above average temperature and the 10th straight month with an average temperature at least 3 degrees warmer than normal. That streak of 13 straight warmer than normal months is consistent with the records from the Twin Cities, as well as the whole US which saw its warmest 12 month period ever from July 2011 through June 2012. Even though July has been farther above normal than the past four months, each of December 2011 through March 2012 were further away from average, topped by March's 14.5°F above normal.

However, individual extreme temperature records in St. Cloud were not as impressive as further to the south. There were only 2 days with record warm temperatures tied or broken: July 2 and 4. There were few record warm highs in July (2) than in January (3) or March (8). The hottest day of the month, July 16 with a 99°F high temperature, broke no records, although it was the third day with a high of at least 97°F this summer. Still, the temperature never broke 100 degrees, as happened twice in the Twin Cities and Redwood Falls. Since 1988, St. Cloud has hit 100 degrees only three times, each time making it to 101: July 3, 1990, July 31, 2006, and June 7, 2011.

St. Cloud hasn't had the vast number of 90-degree plus highs seen further south. The Twin Cities had broken 90 degrees 14 times in July and have logged 24 days with a 90-degree temperature so far this summer. St. Cloud broke 90°F 9 times in July, but there were 15 days with a 90-degree high in 2006 and 9 in July 2005. While the Twin Cities has now racked up 26 days with at least a 90-degree high through August 2, St. Cloud has had only 14 days this summer, short of the 20 days seen in both 2006 and 2007 and far short of the 33 90-degree high days from the last extreme heat year in 1988.

Heat Wave in Early July Not the Most Extreme Either

St. Cloud did string 5 of those days together from June 30 through July 4, the first heat wave in St. Cloud since ut St. Cloud has not made it to 100 degrees and hashose 13 days are similar to the totals we saw during the past two summers and far short (so far) of the summers of 2006 and 2007, the former which had 15 days with a 90-degree high just in July. Also, note that the high has only broken 90-degrees once since our 99-degree high on the 16th. Even in the Twin Cities, which have been hotter than St. Cloud, the highs have only reached 90 degrees twice in the past 14 days.

In this part of the country, a heat wave is defined as having at least three straight days with a 90-degree high or higher. On the average, this happens every other year (this is the 73rd heat wave dating back to 1892). However, only 47 of the 73 has strung at least 5 days together, with the last one being at the end of July of 2006. There were two heat waves of at least 5 days that year, July 12-16 and July 23-31 (tied for the 4th longest on record).

Not making it for a 6th day is yet another demonstration of how rare it is to have 90-degree streaks that long. There have only been 4 streaks of at least 6 days of 90-degree highs over the past 42 years: one in August 1976 (7 days), one in late July to Aug. 1, 1988 (also 7 days), June 1995 (6 days), and the end of July 2006 referenced above (9 days).

The longest heat wave in St. Cloud records was set in the infamous July of 1936. The 14-day heat wave from July 5 through the 18 had 9 days with a high of at least 100 degrees and still holds 9 consecutive record highs.

To rub in that the early month 90's were not a trend, the last 15 days of July after the July 16 99°F high temperature had only one day with a high of at least 90 degrees. Even the Twin Cities only had 2 such days out of the last 14.

Where Was July Extreme? Few Breaks from the Heat

What makes July 2012 so notable is that there were very few periods of true relief from the heat. Nights were not much of an improvement over days as St. Cloud's July average low temperature was 65.0°F, 6.6°F above average. Only July 1935 (66.4°F) and July 1921 (65.3°F) had warmer average records. St. Cloud daily temperature records date back to 1893. In fact, the low temperature only dropped below 60°F 4 times in July 2012, the fewest number since 1935. In June and July combined, there have been only 23 days with a low cooler than 60°F, the fewest in 80 years. While the high temperatures didn't break a lot of records, St. Cloud has gone from June 26 through August 2 without a low cooler than 81°F. The only other July out of the 120 on record without a high cooler than 80 was in 1916. June and July 2012 have only combined for 11 days with a sub-80 high, the fewest since 1930.

The persistently warm temperatures, even at night, helped to keep evaporation, which depends on temperature and wind speed for the most part, higher than expected. Because of this, areas of southern Minnesota that had well above normal rainfall in the spring, have fallen back into the moderate to severe drought category. On the other hand, northwestern Minnesota has missed the bulk of the heavy rainfall from earlier this spring, so their drought conditions have been more persistent, although far short of the red-painted areas on the US Drought Monitor further to the south. The overnight warm conditions also meant that heat relief was hard to come by for humans and animals. Studies show that overnight heat stress can be a large factor in cases of hypothermia, the term for heat-related illness.

St. Cloud did register 5 low temperatures of 70°F or higher in July. During an average summer, St. Cloud gets 3 days with a low temperature of at least 70. There were more 70-degree lows in July 2011 (6) with the record for most July days being 10, set in 1936. The July 4 low was 76°F. That marks only the 54th time St. Cloud has had a low of 75-degrees or warmer, even more rare than 100-degree highs (59). However, 10 of these warm nights have been recorded since 1988 with the previous one on July 17, 2011.

What caused all of the persistent heat with few breaks? The main weather pattern this summer has been persistent hot high pressure from the Southern Rockies and the Middle and Lower Mississippi Valley into the Southeast. That's where the most persistent highs in the triple digits and even some 110's have remained. It's also the areas with the driest conditions and, in the High Plains and Rockies, the areas with the worst wildfires. To the north, across South Dakota, Nebraska, southern Minnesota, Iowa, and southern Wisconsin, the heat has gone on with some periods of slightly less hot, but above normal temperatures. There have been a lot of 90-degree highs with still the occasional triple digit temperature.

The main storm track has mostly remained near the US-Canadian border from the Great Lakes westward. Often, the storm has pushed even further north into the central Canadian Prairie Provinces. That has meant some periods of extreme heat for the Northeast, Ontario, Quebec, Alberta, and Saskatchewan with the main belt of heavy rainfall and severe weather often across the Canadian Rockies and the central Prairie Provinces. This pattern has kept the much cooler Canadian polar air locked up over the Northwest Territories or Hudson Bay for most of the past month and half. So, even when a cool front can make it into northern and central Minnesota, the air isn't that much cooler or drier behind it. It does mean, however, that northern Minnesota has still seen some periods of heavy rainfall in the past 6 weeks, although the heaviest rain amounts are still shown from Brainerd through the Arrowhead, mostly influenced by the flooding storm of June 19-20.

About Normal Precipitation

St. Cloud did end up with above normal July rainfall (3.59 inches, 0.28 inch above normal), thanks mostly to a period of frequent thunderstorms between July 18 and 24. Some areas just to our north again got up to an additional inch more than the St. Cloud Airport. Even SCSU (4.49 inches) gor nearly an inch more than the Airport. Still, the persistently warm temperatures in central Minnesota produced a lot of evaporation, so that any prolonged period without rain browned lawns. Because of this, topsoil moisture was rated as being short in half of Minnesota farms by the end of July. Still, farmers in the northern half of the state as well as North Dakota and the Prairie Provinces are faring better than farms to the south.

    July 2012 Statistics