Weather Wednesday: First frost can happen sooner or later than you might expect

With the calendar turning to September, area farmers and gardeners’ thoughts turn to frost.

It's a virtual certainty that there will be frost some morning during the next few weeks. But every fall is different and weather is highly variable by nature.

Fall’s first frost is defined by the first 32-degree temperature of the season, which may not happen on the same date throughout the region. Year to year, it ranges over about a month. Not only that, but the average first frost has changed over time.

In the Fargo-Moorhead area, the average first frost in the 1880s was in mid-September. Throughout the 1900s, it averaged September 25. But so far in this century, the average has slipped another week to Oct. 2. Again — that’s give or take a couple of weeks.

Most other weather stations don’t have records back to the 1800s, but their records show this same tendency.

Since 2000, Grand Forks’ first frost is coming about a week later than in the 1900s. Mayville and Detroit Lakes show a similar trend, showing that the shift is happening in rural and urban areas.

But in any given year, frost can still happen sooner or later than you’d expect. Just one cold night can happen early even in a fall season that is mild overall. And whether our first frost comes early or late, know that it will have absolutely no bearing on the severity of the upcoming winter season, which is also a virtual certainty.