COLD102707

Hard freeze on the way

First freezing weather of the season to arrive Saturday, about three weeks later than average but not a record.

By Tim Harlow, Star Tribune

Last update: October 26, 2007 - 2:51 PM

Highs in the 80s, copious rains, long stretches of cloudy weather and days with brilliant sunshine - October has dished up a bit of everything except snow and freezing weather. The latter will happen this weekend, the first time this season the mercury will slip below 32 degrees in the Twin Cities.

The month's numerous rainy and cloudy days have helped keep us a bit warmer at night than usual with 36 degrees on Sept. 15 being the lowest reading of the season recorded at Twin Cities International Airport. Normally the first freeze in the Twin Cities takes place around Oct. 6, said Pete Boulay of the State Climatology office.

This year it will happen Saturday night, with temperatures between 25 and 30 degrees expected, the National Weather Service said.

"Sunday morning will be frosty," said Rick Hiltbrand, a forecaster for the National Weather Service in Chanhassen.

The arrival of chilly air is about three weeks later than average, but not a record. The mercury remained above 32 degrees until Oct. 30 in 1973, the latest date for a first freeze since official readings have been taken with thermometers five feet off of the ground at the airport.

From 1891 to 1959, readings were taken with thermometers on tops of buildings in downtown Minneapolis and at the airport. Since cold air can settle closer to the ground, thermometers might have missed some of the coldest nights those years when three times the first frost took place on Nov. 1, Boulay said.

Other than being cold, the weekend looks to be partly sunny with highs in the low 50s, warming to the upper 50s and low 60s Monday and Tuesday. Lows tonight will be 37 degrees and below freezing Saturday. Lows Sunday through Tuesday will be in the 30s to near 40 degrees, the Weather Service said.

Tim Harlow • harlow@startribune.com