Temperatures are expected to drop near freezing overnight Thursday into Friday over much of the Lehigh Valley.
Northampton County is under a freeze warning, meaning frost and freeze conditions could kill crops and vegetation, from 11 p.m. Thursday until 9 a.m. Friday., according to the National Weather Service in Mount Holly, New Jersey. Monroe and Carbon counties are also under the same warning.
🥶 Low temperatures in the 30s to low 40s tonight into Friday morning. This will lead to areas of frost and freezing conditions across portions of PA and NJ. Freeze Warnings and Frost Advisories are in effect. Protect any sensitive outdoor plants tonight! #PAwx #NJwx #DEwx #MDwx pic.twitter.com/el99S213Cl
— NWS Mount Holly (@NWS_MountHolly) October 9, 2025
Temperatures over much of the Lehigh Valley are expected to drop to the mid and even low 30s.
Overnight low temperatures are expected to be just slightly warmer in Lehigh County, which is under a frost advisory from 2 a.m. until 9 a.m. Forecasters said frost could form as temperatures reach the mid-30s. Neighboring Bucks and Berks counties are also be under the same advisory.
Residents should take steps to protect plants from the cold, the weather service said.
The cooler weather follows a cold front that moved through the region, ending several days of unseasonably warm weather with daytime highs around 80. Thursday’s high temperature is expected to be only 56 degrees, according to the weather service forecast.
Friday and Saturday will be slightly warmer, with daytime highs around 60. Here is the extended weather service forecast:
Thursday: Sunny, with a high near 56. North wind around 10 mph, with gusts as high as 20 mph.
Thursday Night: Widespread frost after 11pm. Otherwise, clear, with a low around 32. North wind around 5 mph becoming calm in the evening.
Friday: Widespread frost before 8am. Otherwise, sunny, with a high near 58. Light and variable wind becoming south 5 to 10 mph in the morning.
Friday Night: Mostly clear, with a low around 40. South wind around 5 mph becoming calm.
Saturday: Partly sunny, with a high near 62. Light east wind becoming southeast 5 to 10 mph in the morning.
Saturday Night: A chance of showers. Mostly cloudy, with a low around 47. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.
