The old-time farmers had their rules of thumb. One was not to put warm-weather crops in the ground until at least Good Friday.

The reason? To avoid the threat of a late frost.

They may have known a thing or two.

Good Friday is this week, but a cold snap could send temperatures below freezing Monday and Tuesday nights in Troup County.

Today’s high in the mid-70s in LaGrange should mirror that of Saturday. But Monday and Tuesday are a different story. Highs both days are around 50, with the mercury forecast to dip to 31 Monday night and to the lower 20s Tuesday night, threatening the record of 29 set in 1971.

The culprit is a storm system over the Upper Plains that is expected to dump 6 to 15 inches of snow on Iowa, Minnesota and Wisconsin by this evening.

James Wilson, lead meteorologist for the Weather Channel, said strong to severe thunderstorms are expected today across parts of the nation.

“The main threats from the thunderstorms over the Ohio Valley, Tennessee Valley and northern portions of the Southeast are strong wind gusts and hail,” he said.

By Monday, colder air spills into the Southeast and northern Florida with gusty winds, he said.

“It should get cold enough Monday night and early Tuesday to cause accumulating snow in the mountains of Tennessee, North Carolina, northern Georgia and northeastern Alabama. Several inches of accumulation are possible by Tuesday morning,” Wilson said.

The cold snap means bringing potted plants inside, but gardeners don’t have that option.

For those who already have planted crops and other plants, experts advise keeping mulch handy and paying attention to weather forecasts to help avoid damage.

The normal extremes for this time of year in LaGrange are 75 and 48.

More-seasonable temperatures are expected by the end of the week.