A chilly Canadian air mass has come for a short visit, WeatherWorks says.
As it tends to do, the weather is going to test your patience this week.
What a WeatherWorks meteorologist based in Hackettstown describes as a "pretty cold Canadian air mass" will visit the Lehigh Valley and northwest New Jersey until midweek.
And while Sean Rowland says such an event isn't terribly rare for May -- it happens every couple of years, he said -- this one could challenge record lows (33 today, 29 on Tuesday).
The Canadian air tends to drop temperatures 15 to 20 degrees below normal, he said. But it was 80 degrees last Friday and could be 80 again by Thursday, he said.
This current cold snap is "completely unrelated" to the weather that kept much of the early spring cooler than normal. Actually, up to this point, May has been fairly average, he said.
While the region was in a frost advisory, the temperature just before 7 this morning was 40 degrees. The forecast low tonight is 32, the National Weather Service predicts.
A frost, Rowland said, could come in the mid 30s, because the ground can be colder than the air, leading to ice crystals forming. A hard freeze happens at 32 degrees or below, he said.
Either way, if you have temperature-sensitive plants, either cover them or bring them inside.
"That's pretty much the main piece of advice" with the current forecast, he said.
It will get up into the mid-50s today and be back to a normal 70 by Wednesday, forecasts indicate.
As we've been asking all year, when will the cold be put away until late fall?
"In the second half of May and early June, (cold days) will be few and far between," Rowland said.