The National Weather Service is warning that temperatures could drop to near freezing in the greater Tri-Cities area from 2 to 9 a.m. Thursday.
Frigid temperatures for spring could affect some plants and newborn livestock, it said. It also could possibly damage unprotected outdoor plumbing.
In the Tri-Cities the low is forecast to be 34 degrees, although it could be a couple of degrees cooler. In outlying areas, including at higher Eastern Washington elevations and communities such as Connell and Hermiston, Ore., temperatures are forecast at freezing or a little cooler.
Normal lows for the Tri-Cities in the third week of April are about 39 degrees.
Lows should be warmer for the rest of the week, with lows in the 40s, according to the weather service.
Highs should warm from the 60s to the 70s for the start of the next work week.