We have a cold night coming tonight. It will likely be cold enough at many places to kill any frost-sensitive plants.
I have a few ways we can figure out if your location will have a killing frost or freeze.
Firstly, here are the areas officially under a freeze warning or frost advisory.
Freeze warning in purple and frost advisory in blue
The National Weather Service has the freeze warning for Clare and Cadillac to Houghton Lake, Grayling, Gaylord and the Mackinaw City area. A freeze warning means the temperatures are forecasted to drop below 32 degrees.
A much larger area has a frost advisory from Oakland County, the Lansing area to Allegan County and all areas through central and northern Lower Michigan. The frost advisory area could have temperatures dropping to 35 degrees. Remember that an official temperature of 35 degrees at six feet above the ground can have freezing temperatures right on the ground.
The wind forecast is just a touch encouraging for southern Lower with an eight mile per hour wind at sunrise. This wind could help stir up the lower part of the atmosphere and keep temperatures above freezing. The wind can also keep frost from forming. The northeast wind also means Bay City will probably avoid a frost since the Saginaw Bay water has warmed up.
Wind forecast at 5 a.m. Thursday shows still a breeze in southern Lower which could help with keeping temperatures a degree or two warmer.
Here is the best model at forecasting cold mornings and the location of the cold. It shows the interior part of the Thumb and south-central Lower Michigan have to worry about our gardens.
Low temperature forecast for Thursday morning, May 25, 2023 from what is usually the best model for cold mornings.
So here’s how I think you can figure out if your location will have frost or freezing temperatures. At 5 p.m. today find out what the temperature is at your location. Subtract 25 degrees from your actual 5 p.m. temperature. This 25 degree temperature drop would be the most that your temperature could fall overnight. If you come up with 35 degrees or less you better cover the plants that will be killed with a frost.
If you have some wind continuing near midnight you can add back on three degrees.
So basically if the temperature at your garden isn’t at least 60 degrees at 5 p.m. you have a strong chance at frost.
Tomatoes, peppers, cucumbers, all squash, pumpkins and basil will need to be covered to not be killed.
Let’s look at the temperatures after 6 p.m. on the Michigan Weather Facebook group page to see who is set up for a frost. With this one I’d error on the cautious side and cover your frost-sensitive plants. Don’t take the cover off because you may need it again Friday morning. Then we should be clear of frost for the growing season.
