Just when you thought it was safe to go back into the garden, another spring chill is settling across the Upper Midwest. For the first time in many weeks, Minnesotans are once again reaching for the jackets as the mercury dips into chilly territory. Average lows for Minnesota this time of year range from the Upper 30 up north and the upper 40s down south.
Its not uncommon to be threatened with frost this late in the season. In fact, the latest we have hit freezing in the metro has been May 13.
However, no matter how uncommon the cold may be, its still sends shivers up the spines of gardeners and warm enthusiasts alike.
The Minnesota Department of Natural Recourses has compiled a web page just full of the latest freeze dates possibilities across the state. Check it out at http://www.dnr.state.mn.us/climate/summaries_and_publications/freeze_date.html
FROST AT 39°: How can that be?
It's a chilly night but temps are in the 30s, so how can something frost be around if the temperature is not at or below freezing? It all comes down to location, location, location. Most thermometers are reading the air temperature at about four feet off the ground. There are many areas, that are mostly low lying and undisturbed, that can be just a tad cooler. When you're talking just a few degrees of separation between chilly and frozen, the areas can bridge that gap. Elements like wind and humidity levels and affect the rate of evaporation, which is usually the mechanism that takes the temps to the 32° threshold.
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