Daryl Ritchison, WDAY, Published May 08 2012
Weather Talk: Climate makes it hard to know when to plantFrom 1881 through 2011, the average last frost in Fargo-Moorhead was on May 13. The current 30-year average (1981 through 2010) is May 8. Using either average, this tends to be the time of year when we record the last freezing temperature of the season.
The standard deviation is 12 days, which in simple terms means there is a window of about three weeks when the occurrence of that last frost would be considered “normal.” Of course, three weeks in our climate can easily mean the difference between a great crop and no crop at all.
All these statistics are based on a 32-degree temperature, but frost can occur with temperatures warmer than the official measurement. If you use 34 degrees, that normal range extends out to nearly one month.
This makes it difficult to know when to plant, but the reality of our climate is that if you wait until it is safe to plant, you will never plant. So at some point, you just have to play the odds.
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