The National Weather Service in Pittsburgh has issued a frost advisory for areas north of Allegheny and Westmoreland counties Sunday night.
Allegheny and Westmoreland could fall under a frost advisory Monday night into Tuesday morning, when northern areas will be under a freeze watch, meteorologist Bill Modzelewski said.
Counties covered by Sunday night’s frost advisory include Beaver, Butler, Armstrong and Indiana. With lows on average around 40 degrees, Allegheny and Westmoreland counties are not included.
Frost Advisory tonight as temps drop into the mid/upper 30s. Freeze Watch in effect Mon night/Tue morning as temps fall to near/below freezing. Areas of frost are expected for the remainder of the area outside of the freeze watch Mon night/Tue morning. pic.twitter.com/T5hGZ3KTtx
— NWS Pittsburgh (@NWSPittsburgh) May 11, 2026
As issued Sunday, the freeze watch for Monday night into Tuesday morning includes Butler, Armstrong, Indiana and Somerset counties. In those areas, the low will get down to 30-to-32 degrees, Modzelewski said.
While Modzelewski said it’s unlikely that the freeze watch will expand, he said the weather service may issue a frost advisory for the remainder of the area, where the low will be in the mid-30s.
Tuesday morning should see the end of any freeze or frost potential for the week, Modzelewski said. Temperatures are forecast to warm up later in the week into next weekend, with highs reaching the lower 80s and lows in the lower 60s to upper 50s.