August 2013 Saint Cloud Weather Summary

Summer Temperatures in Fits and Starts, But Another Late Summer Dry Spell

Saint Cloud Weather Summary for August 2013 and Summer 2013

Issued: Monday, September 2, 2013 11:03 AM

6th Driest August, July-August Combo

While summer weather nearly had a one month sabbatical in July and August, the dry trend that began in July intensified in August. Only 0.85 inch of rain fell at the St. Cloud Regional Airport, nearly three inches below the average total of 3.79 inches. This made August 2013 the sixth driest August in St. Cloud records. In fact, only 2.28 inches has fallen since July 1, the 6th driest July-August in St. Cloud records and the driest in 32 years. This continues a trend of dry spells that have hit St. Cloud from some time in the summer and continued into some part of the fall. Five of the past six years have had a dry spell during which St. Cloud rainfall was at least four inches below average. So far, the 2013 dry spell has the second largest deficit in those 6 years and has built up the shortfall in the shortest time.

The dry conditions has changed a wet spring into moderate drought conditions, as seen in the US Drought Monitor. Through August 29, more than 55% of Minnesota ranked in moderate drought with 66% of subsoil moisture reported as being short in the latest Minnesota Weekly Crop Report. Since the last week of June, much of central Minnesota has seen rainfall 5-7 inches behind average, according to the Drought Report from the Minnesota State Climatology Office.

The one saving grace of this dry period has been below average incidents of severe weather. The most widespread severe weather outbreak in August was a hail storm that basically paralleled I-94 on its south side from Ortonville into the Twin Cities. There was a weak tornado touchdown near Hill City in Aitkin County on August 29, but there have only been 9 tornado reports in Minnesota so far.

After A Month Off, Summer Resumed in Late August

August also finally broke the vacation from summer weather that began in mid-July. The average St. Cloud temperature in August was 69.7°F, 1.9°F above average. That warmth marked a huge turnaround in the last two weeks of August.

Heat Wave Produces Six Daily Temperature Records, But Not Extraordinary Heat

Through August 15, St. Cloud's average temperature was 64.0°F, 5.1°F cooler than average. That statistic, had it held through the month, would have ranked as the 9th coolest August in St. Cloud records. On August 19, St. Cloud completed a string of 28 straight cooler than average days. The high of 88°F was the first day with a high of at least 85 degrees since July 22. Conditions rapidly turned around at that point. The last 16 days of August averaged 74.9°F, which would have ranked as the 4th warmest August on record. During August 19-29, there were 7 days with a a high of at least 90 degrees. Only 6 days had 90-degree days before then. During these 11 days, the high was never cooler than 85 degrees and there were only two days with a low cooler than 60 degrees. This included a four-day heat wave August 24-27, during which 6 daily record warm temperatures were broken. There were also three nights during which the low temperature stayed at 70 degrees or warmer. Those warm nights produce the worst heat stress for people who don't have the opportunity to cool off during a heat wave. The hottest temperature was the 95°F, which broke the August 26 record warm high. However, that merely tied May 14 for the hottest temperature of the summer. The heat wave was far short of the record August heat wave (7 straight days on August 18-24, 1976) and did not equal the most recent heat wave of 5 days during June 30-July 4, 2012. The persistent heat produced one of the hottest average high temperatures in the State Fair's history.

Overall, the temperature trend for the summer showed a one-month break in the heat from mid-July to mid-August. This produced a summer (June 1-August 31) average temperature of 68.5°F, 0.6°F above average.

The hot temperatures forced evaporation rates higher, so the effect of the dry conditions were worse during the heat the second half of the month. This frequently produced high fire danger rankings in northern and central Minnesota.

The major weather pattern shift was causing by a drastic shift of the steering winds. During the first half of the month, there were a series of storm systems moving southeastward from the Canadian Rockies into the Northern Plains and most of the East Coast. While the bulk of the rainfall missed Minnesota, unlike what happened during the spring, this did allow cooler air masses to move from central Canada into the Northern Plains. During the second half of August, the steering winds stayed near the US-Canadian border. During the heat wave, the strong high pressure area that had given the heat and dry conditions to the Southern Rockies and Texas for much of the summer moved towards Nebraska, keeping all, but the Canadian border area in the searing heat.

Relief At September Start, But Warmer Than Average to Return

The bulk of the Labor Day weekend has seen major relief from the heat as highs have been knocked down into the 70's and overnight lows have dropped into the 50's and 40's. However, most forecasts have the main belt of steering winds being shoved north of the Canadian border again to the west of the Great Lakes. That pattern would bring temperatures back into the 80's by mid-week. At this point, 90's look to be out of the question, but this pattern could bring more frequent thunderstorms at least into the general area, so it is possible that we might see better chances of important rainfall by late in the week.

    August 2013 Statistics

Summer (June 1-August 31) 2013 Statistics