Season's first frost for much of Minnesota this week

Temperatures in 30s in most of the Twin Cities by Wednesday morning

Forecast low temperatures Wednesday
Forecast low temperatures Wednesday.
National Oceanic and Atmospheric Administration

‘Tis the season.

It’s that time of year when colder air masses visit Minnesota with increasing frequency and intensity. The first frosts of the season typically work southward through Minnesota in late September and October.

Our inbound Canadian air mass will bring freezing temperatures to much of Minnesota this week. I expect frost advisories will go up later this afternoon for areas of central Minnesota. Temperatures will fall into the 30s across most of northern and central Minnesota Tuesday morning.

Forecast low temperatures Tuesday morning 2
Forecast low temperatures Tuesday morning
NOAA

A low near 43 degrees Tuesday morning will be the coldest of the season so far. We bottomed out at 47 degrees at Minneapolis-St. Paul International Airport last Thursday morning.

Widespread frost Wednesday morning

Wednesday morning will be the coldest this week. Temperatures will fall into the 30s for most of Minnesota, and even most of the Twin Cities.

Some Twin Cities suburbs could approach the freezing mark early Wednesday, but I think the inner core of the Twin Cities will bottom out in the upper 30s.

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Forecast low temperatures Wednesday
Forecast low temperatures Wednesday
NOAA

Expect frost advisories to be issued Tuesday that will include the Twin Cities for Wednesday morning.

When does Twin Cities metro first hit freezing?

Freezing temperatures are common in northern Minnesota in late September. We’re rapidly approaching the median date of the first 32-degree temperature in the Twin Cities.

First 32 degree in fall
Median date of first 32-degree temperature in fall.
Midwest Regional Climate Center

Weather records at Minneapolis-St. Paul International Airport show the long-term median for the first 32-degree temperature in fall is about Oct. 8.

msp-first-32
Minnesota State Climatology Office

Thanks to the urban heat island, most Twin Cities suburbs typically see the first frost earlier than the airport and downtown urban core of the Twin Cities.

Cover up those tender plants if you want to keep them around. It looks like a warming trend will boost temperatures back into the 70s late this week.

Forecast high temperatures Friday
Forecast high temperatures Friday.
NOAA

And temperatures are likely to remain well above freezing in the Twin Cities until at least early next week.

Stay tuned.