Above normal temperatures throughout much of March and April has led to an early onset to the growing season across north-central and northeastern South Dakota and west-central Minnesota. In fact, the growing season in many locations may be as much as 1 to 2 weeks ahead of normal. As such, many folks may have taken advantage of these warmer conditions and started gardens or planting operations. However, in many locations, freezing conditions are still possible this spring which may pose a threat to many agricultural interests (see dates below).
The NWS in Aberdeen issues several products to alert users for the potential for frost or freeze conditions. The following products will begin to be issued on (and after) May 7th:
Freeze Watch: Issued when conditions are favorable for temperatures to fall below 32 degrees Fahrenheit during the next 12 to 48 hours resulting in the possibility for significant damage to unprotected vegetation.
Statistical Dates of the Last Spring Frost/Freeze
To assist the agriculutral community, below is a table that summarizes the last calendar day when temperatures of a given threshold are expected to be met. For example, in Aberdeen, the average (or mean) date when temperatures are last expected to fall to 32F occurs on May 13th. Similarly, 90 percent of time, temperatures in Aberdeen will have fallen at or below 28F by May 18th.
Mike Fowle - SOO