First frost of the season possible in some areas on Saturday

Even with above freezing air temperatures, frost can still form
Average "first frost" dates
How is frost formed
Posted at 5:44 PM, Sep 09, 2022
and last updated 2022-09-09 20:43:22-04

Record-breaking heat and destructive fires earlier in the week were deceiving when it comes to predicting what is to come this weekend.

Temperatures may run as much as 70 to 80 degrees cooler Friday night and Saturday morning than what central Montana experienced Wednesday afternoon.

Frost is a possibility in several towns and cities throughout the area. It is not unheard of the average first frost of the season is generally in early to mid September.

In Great Falls and Helena, the average first frost is typically in late September. However, it is possible both cities wake up to patchy frost Saturday morning

Even if your town or city is not forecast to reach the freezing mark, frost is still a possibility and you should consider protecting sensitive plants.

Official air temperatures are taken by an ASOS (automated surface observing system) station and in an effort to keep weather records consistent, all ASOS stations are placed around 5 feet above the surface.

In an environment with clear skies and light winds, cooler air sinks to the ground making the surface a touch cooler than the actual air temperature. If the surface is cold enough, it freezes. However, most of the time the temperatures would need to be, at most, in the mid 30s.

According to Forde's nursery in Great Falls, annuals and vegetables are most vulnerable to frost and freeze. Make sure to pull your plants indoors or cover them with a blanket or sheet overnight.

After the initial morning chill, we are going to have gorgeous weather with lots of sunshine, good air quality, little wind, and comfortable temperatures in the 70s. This is definitely the day to be outdoors this weekend:

Warming back up this weekend

On Sunday, the weather is still going to be pretty nice, but it is going to be warmer as highs are going to be in the mid to upper 80s and low 90s, and the smoke is going to increase throughout the day, which means that the air quality will gradually get worse as the day goes on. There is also going to be a little bit of a breeze on Sunday with sustained wind speeds between 5 and 20 mph, and this wind is going to be coming out of the southwest. We are also going to have mainly sunny skies on Sunday.


How is frost formed