10 Coldest Septembers Ever Recorded in Montana

Fall in Montana is when we really start to see the transition from summer to winter.

Daylight Diminishes: Preparing for Shorter Days

Depending on where you are in the state, we're going to lose roughly 90 to 100 minutes of daylight throughout September, and that loss of daylight will continue as we make our way toward the first day of winter.

Autumnal Equinox: Marking the Start of Fall

Of course, September also brings us the first official day of fall. The autumnal equinox arrives on September 22nd, marking the official beginning of the fall season.

This is also the time of year when we start keeping an eye on those first frost dates.

According to the Old Farmer's Almanac, much of Montana can expect overnight temperatures to dip toward freezing or below, as we move through September. Exactly when that first frost arrives depends on where you live, but those cooler nights are definitely becoming more common.

When it comes to daytime temperatures, September can be one of the wildest months of the year in Montana.

A listener called me the other day and said something that perfectly describes September here:

You walk outside in the morning wearing a short-sleeve shirt, realize you're freezing, and wish you'd grabbed a jacket. Then by 10 o'clock, you're wondering why you're wearing so many clothes because it's warming up quickly.

That's September in Montana.

Layering Essentials: Dressing for a Variable Season

Layers become your best friend.

We can have chilly mornings followed by afternoons in the 70s or even 80s. But as we get closer to October, we'll gradually start seeing those temperatures cool off, and winter won't seem quite so far away.

Historical Context: Cold Septembers in Montana

September has certainly had some downright cold years in Montana.

NOAA has been keeping track of Montana's climate records going back to 1895, and when you look at average temperatures — meaning the daytime highs and overnight lows averaged together — some Septembers really stand out as being particularly cold.

The coldest September on record for Montana was 1965, according to Extremeweatherwatch.com.

That year, the statewide average high temperature was just 53.4 degrees, while the average low was 33.8 degrees.

Think about that for a second.

That's the average for the entire month — not the coldest day of the month.

The Dual Nature of September: Summer vs. Winter

So, yes, September can still feel like summer in Montana. But we've also had some Septembers that felt an awful lot like winter was already knocking on the door.