Yesterday’s high in southeast Michigan was 62 degrees. Today’s expected high is 27. That’s a difference of 35 degrees in high temp. Granted, that’s probably the most extreme swing ever around here, but it seems like every year we get variations of as much as 30 degrees in high temp across a day or two in the dead of winter.
I’ve never seen variations like that in the summer months, e.g. a high of 100 one day and then a high of 70 a day or two later. Why is the day-to-day-variability in high temps so much greater for winter than for summer?
where you are the jet stream is moves above and below. the edges of the stream can go halfway up into Canada and halfway down into the USA. the Rocky Mountains and Gulf of Mexico provide direction to lots of wind activity.
Depends on when your most recent cold front moved through (which as my namesake johnpost indicated is dependent on the jet stream’s location and shape in your area). If you have high pressure sitting over you for several days with constant sunshine it will warm things up pretty well. In summer there’s simply no huge pool of cold Arctic air to come southwards to cool things off like that.
As far as I can tell, it’s because in the absence of any sort of cold fronts, the temperature in most places is higher than sometime after a cold front.
So for example, here in Dallas, the usual winter temps are highs somewhere in the mid-upper 50s, and lows in the upper 30s and 40s, which is higher than the average that the NWS will quote you.
However, when a cold front comes through, we may have a week with highs in the 20s and lows in the teens.
It doesn’t seem to work that way in the summer though- we sit under a high pressure system for months on end, and the temps are steadily somewhere between about 95-105 and the lows are around 80 from about mid-June through mid-September.
Note that the jet streams shift latitude during the year. During the summer the main one over the US retreats north and comes back down during the winter. This means more fronts, rapidly moving storms, etc. going on during the winter than the summer for a large part of the US.
On the Pacific coast, this means that those big old Pacific storms tend to favor Canada in the summer, the PNW in the fall and spring, and California in the winter. (Lots of variation, especially in El Nino years.)
There are also stationary systems like the Bermuda High that crop up during the summer that help block large air masses from moving around. So summer tends to be a lot more “consistent” than winter. We go weeks at a time in the summer with forecasts like “Hot, hazy and humid. Highs in the upper 80s. Chance of an afternoon thunderstorm.”
Yesterday morning temp: 65F, this morning 33F. It was breezy last night.
I ran a quick check on Minneapolis, which isn’t quite the same, but has a similar climate to Michigan.
I checked the daily high temperature swings for 50 years. The highest swings in that period were 43, both in January. (One a drop from 34 to -9 the other a climb from -14 to 29.)
There were 62 swings of 30 degrees or more, with none in July or August. By contrast, over half were found in the months December, January, or February. 57 occurred in the October-April period, with 5 outside of that period. There were 2 in May, 2 in June, and 1 in September. All 5 of these were massive drops, probably accompanied by severe weather.
My conclusion: I’d be willing to bet that a formal study of midwestern climate temperature swings would find convincing evidence that more occur in Winter, confirming the OP’s guess. I don’t know enough about weather to know why, but the other posts sound reasonable.
In the summer, temperatures are more similar based on latitude. This is because the higher latitudes near the poles are getting more daylight hours than the lower latitudes. This is offset by the higher sun angle at the lower latttudes.
In winter, the higher latitudes are having shorter daylight hours and a lower sun angle while the lower latitudes have high sun angle and longer daylight hours.
The result is that in the winter the air masses have a greater temperature range. Once the air masses start moving around it makes for more variation in winter.
Another factor is that, in most locations (short of extremely arid areas), the amount of water vapor in the air is much, much higher in the summertime. That water vapor largely acts as a “floor” for how low the temperature can get – as air gets colder, it can’t hold as much water, and, as the temperature drops, the air reaches its saturation point, or “dewpoint”.
So, in the summertime, in many places, the air temperature simply can’t drop below 40 or 50 degrees, because that’s the dewpoint. On the other hand, there’s no reason that dry, winter air can’t get substantially warmer, which is why you see the bigger swings in that season.
Whoa. That is crazy. And I thought Chicago going from 61F (Tue afternoon) to 1 (morning today. ETA: which is a Friday morning, in case someone years from now comes upon this thread and doesn’t feel like consulting a calendar) was impressive.