St. Cloud, MN Weather Forecast

Upcoming Heat Not Likely to Break Records, Because....

The hottest period (temperature-wise) of the year so far will begin this weekend. We will likely see highs well into the 90's with perhaps a few 100's. The uncomfortable dew points will likely keep low temperatures at least in the 60's. And, the persistent southwest wind that will develop by Sunday could keep lows in the 70's. It's those 70-degree plus nights that pose the biggest risk for people without access to fans and air conditioning, since the body cannot cool sufficiently.

...of 90 Years Ago

However, record warm temperatures will be nearly impossible. That's because the hottest weather in St. Cloud records happened 90 years ago in mid-July (set NWS Twin Cities NOAA data to St. Cloud area, daily data for a month, and 1936-07). Between July 6 and July 17 of that year, every high temperature was at least 97 degrees, with 9 days over 100 degrees.  More importantly, every high between July 6 and 16 still stands as a daily temperature record. That includes 107 on July 13, tying St. Cloud's hottest temperature on record. 8 of the lows were in the 70's, 7 of which still stand as low temperature records. This was part of the 'Dust Bowl' era in the 1930's, a decade of persistently hot summers (5 of the 10 hottest summers in St. Cloud records) with dry conditions. However, the winters were often colder than average, so only 1931 ranks among the 10 warmest years in St. Cloud records. Note that 7 of the 11 warmest years have occurred during our spell of warmer temperatures since 1997, including 3 during the 2020's. These years have been more humid during the summer (hard not to be more moist than the Dust Bowl years) and persistently warm during the seasons outside of the summer.

Harder to get into 100's, Especially With More Moist Low-Levels

The records are unlikely to fall this year because we will still have a fair amount of moisture in the air. Water vapor in the air absorbs some of the sun's heat before it can get to the ground. Also, the corn is approaching the tasseling stage. That's when the food-making process is the strongest. That will put more water vapor into the air, since the plants put out both that moisture and oxygen.

On the other hand, it is the reason that overnight temperatures stay quite warm. Thus far in July, the average temperature has been 2.6 degrees above average with persistent lows in the 60's as responsible as the mid-80's highs for the warmth.

The 10 days of at least 100 degree temperatures in 1936 comprise one-sixth of the 60 highs of at least 100 in St. Cloud records.  1931 had 11 such highs. On the other hand, St. Cloud has only hit 100 degrees 11 times since 1950, 7 of those days in 1988.

Not Hot Yet Today and Perhaps Tomorrow With Scattered Thunderstorm Chance, Mainly Tonight

We have two days before we begin the true heat. There have been strong thunderstorms developing overnight, as they typically do when really hot air moves over the top of warm and humid air. Already, 90's moved into South Dakota and Nebraska yesterday (see yesterday's 4 PM NWS WPC North America zoom-in map), so the overnight storms developed in North Dakota, and have been blossoming into eastern South Dakota and western Minnesota (see College of DuPage continental US clean infrared satellite loop). Other growing storms have developed in Kansas and Nebraska. The radar echoes have had trouble growing into Minnesota so far (see College of DuPage north central US radar loop), but we will have a small chance for a shower or thunderstorm this morning (1 in 5), plus some lingering clouds for a while this morning. 

There will be a better chance of showers and thunderstorms late today and especially overnight as the front over Manitoba last night (see band of green and yellow clouds on the College of DuPage North America clean infrared satellite loop) moves further to the east, so tonight's round of storms will develop a bit further to the east than on Thursday night. A few of these storms could produce some large hail, but these will be isolated.

The latest forecasts still have a chance of temperatures reaching 90 degrees tomorrow. However, the warm front is likely to come through Saturday night (still a chance for an isolated shower or thunderstorm). 

Worst of Heat Effects May Be in Northern Minnesota, So Be Prepared If You Have Canoeing, Camping or Other Outdoor Travel Plans

This still will be a rare heat wave. The hot high is forecast to be in Minnesota and North Dakota by Monday, so even northern Minnesota will suffer in the heat, possibly beginning tomorrow and lasting through Tuesday (see red areas on the NWS Heat Risk Forecast for Saturday through Tuesday). There is actually a better chance for 100 degree highs in western and northwestern Minnesota than in central and especially east central Minnesota. That will make the heat quite taxing for anyone camping or in homes and businesses without air conditioning. The National Weather Service already has an extreme heat watch in effect for northwestern and west central Minnesota from Sunday morning through late Monday night, including the Red River Valley and Lake of the Woods. Expect more watches with at least heat advisories covering the rest of Minnesota for Sunday and Monday, at least.

So, it would be a good time for communities to review both how to prepare for intense heat and how to protect residents from overexposure to the sun.

When Will the Heat Break? Not Likely Before Mid-Week (and That Might Be Early)

The high is forecast to slowly push southeastward. That would allow the main storm track, likely over the central Canadian Prairie Provinces early next week, to push back into or near Minnesota. Also, the big clockwise circulation, now centered over the Intermountain Region (see College of DuPage North America mid-level water vapor loop), will pull some of the Gulf of California moisture producing daily thunderstorms in central and now northwestern Mexico (see College of DuPage North America clean infrared satellite loop) northward along the eastern Rockies, likely at least getting into Montana by the middle of next week. The shower and thunderstorm chance doesn't appear to be great, but that would trigger at least scattered showers and thunderstorms, which could proceed into at least northern Minnesota sometime during the second half of next work week (see Days 4-7 of the NWS WPC quantitative precipitation forecast). Even if parts of Minnesota get missed by the storms, parts of the state could have lingering clouds for at least the first part of the day, which could reduce the limit the potential highs to the lower 90's or even the 80's. That's the reason for the smaller red areas in the NWS Heat Risk Forecast for Wednesday and beyond. This could also be wrong if the high remains near Minnesota for longer. 

Helpful Rain for the Past 2 Weeks, But Drought Likely to Get Worse Over the Upcoming 7 Days

This is the worst case scenario for easing the drought that has St. Cloud more than 6 inches behind on rain since last August. There was some help over the past week in the moderate drought areas of southern Minnesota, seen on the two week comparison of the US Drought Monitor. (this product also worries me, since the worst drought conditions, red on the current US Drought Monitor, have been reached in only a couple of years of rain shortage. I don't want to even think how well we would be prepared for a series of years like the 1930's). However, we won't see much rain from now through the heat wave and will lose a lot of ground moisture due to evaporation from the hot temperatures.