The NWS has issued a Frost Advisory for tonight/tomorrow morning for some portions of northeastern OK and adjacent areas in Kansas, Arkansas and Missouri. I'll link the NWS map from NWS-Tulsa below. You can click on any county to see the forecast and can click on the Frost Advisory link on each county's page to see the timing of the advisory for your area.
NWS Tulsa
Remember that, for several reasons, you can have frost on your plants even when the temperatures remain several degrees above freezing. I know we have had this happen in southern OK numerous times on nights when the temperature was as warm as 37 or 38 overnight, and maybe once at 39 degrees. It is very frustrating, and is much better to cover up the plants out of an abundance of caution than to walk out and see unexpected frost on your plants the next morning. (If that happens, I hurriedly hose the frost off the plants hoping to prevent more damage. I don't know if it really helps, but I think it does.)
Good luck to all of you in the Frost Advisory area.
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