Winter isn’t just coming in the Twin Cities – it’s a week overdue.
Minneapolis-St. Paul International Airport has yet to report the first fall freeze this year, though it is imminent as temperatures continue to drop into the 30s at night. Much of outstate Minnesota has already experienced their first frost, a sign that the growing season has officially ended.
Since 1960, MSP Airport has recorded an average first freeze date of Oct. 6. Rochester and International Falls fell within that range this year – albeit nearly a month later than they typically see frost on the ground – documenting a freeze Oct. 8. Duluth followed the next day, also past due.
Experts say it’s hard to pinpoint what might cause such a delay in freezing temperatures. One factor might be the amount of precipitation Minnesota had this year, which has saturated the ground for nearly four months straight.
“When you have a lot of moisture, it’s more conducive to keeping more heat in the soil,” said Tony Zaleski, a meteorologist at the National Weather Service in Chanhassen. The Twin Cities collected nearly 8 inches of rain in August, nearly twice as much as a year ago.
The earliest reported freeze at MSP since record keeping began in 1938 was Sept. 4, 1974. Since then, freeze dates have steadily pushed further into the season, landing in mid-to-late October over five decades, according to a Star Tribune analysis of data from the Midwest Regional Climate Center.
Of the three outstate cities we analyzed – Rochester, International Falls and Duluth – Rochester consistently recorded later freeze dates than the others, including MSP, because it is the furthest south. International Falls, nearly 400 miles north of Rochester on the Minnesota-Canada border, broke its earliest freeze date record in 2004, documenting a frost on Aug. 22. The freeze date title of Aug. 24 had previously held its record for nearly 30 years.