Weather
Western Pennsylvania Frost Alert: Lows Near 33° Oct 18-19
Pittsburgh, PA – A sharp autumn cooldown is expected to bring widespread frost across western Pennsylvania early Sunday, Oct. 18, followed by another possibility of frost Monday morning. Temperatures
By Evan Cross · 2026-10-16T07:26:17.164Z
Pittsburgh, PA – A sharp autumn cooldown is expected to bring widespread frost across western Pennsylvania early Sunday, Oct. 18, followed by another possibility of frost Monday morning. Temperatures in Pittsburgh could fall to approximately 33 degrees Saturday night, putting sensitive plants and outdoor vegetation at risk as colder air settles across the region. The National Weather Service has highlighted the developing frost threat in its Hazardous Weather Outlook, making the weekend temperature change an important concern for homeowners, gardeners and residents preparing for colder mornings.
According to the National Weather Service in Pittsburgh, a strong cold front crossing the region Friday will usher in substantially cooler conditions by Saturday. The city's forecast calls for a high near 52 degrees Saturday, followed by clear skies and a low around 33 degrees Saturday night. Widespread frost is expected before 8 a.m. Sunday. The Hazardous Weather Outlook also identifies another possible round of frost Sunday night into Monday morning, although Pittsburgh's forecast low Sunday night is somewhat warmer, near 37 degrees.
Widespread Frost Expected Sunday Morning Sunday's frost potential represents the most significant upcoming weather development for the Pittsburgh area. Temperatures near the freezing mark can allow frost to form on exposed surfaces, particularly where skies remain clear and winds become light. The forecast calls for northwest winds around 5 mph Saturday evening, becoming calm later, creating conditions favorable for temperatures to fall near the surface.
The frost threat extends beyond Pittsburgh. The National Weather Service's Hazardous Weather Outlook covers western Pennsylvania and northern West Virginia, including communities across Allegheny, Beaver, Butler, Washington and Westmoreland counties. However, temperatures will vary by location, and the Pittsburgh point forecast should not be interpreted as an exact prediction for every community. Valleys, rural neighborhoods and sheltered locations may experience different conditions than densely developed urban areas.
Residents with sensitive flowers, vegetables and outdoor plants should consider protective measures before Saturday evening. Lightweight frost coverings may help reduce exposure, while movable potted plants can be brought indoors or placed in sheltered locations. Frost can damage vulnerable vegetation even when official air temperatures remain slightly above 32 degrees, making the expected low near 33 degrees particularly relevant.
Another Frost Risk Could Affect Monday Morning The colder pattern may continue into Monday, Oct. 19, when patchy frost is forecast before 8 a.m. in Pittsburgh. Temperatures Sunday night are expected to fall near 37 degrees, providing another opportunity for frost to develop in favorable locations. The National Weather Service has identified this second frost possibility in its extended hazardous weather outlook, although the forecast does not indicate widespread freezing temperatures across the city.
Monday's morning frost potential may be most noticeable on lawns, parked vehicles and exposed vegetation. Drivers traveling Interstate 376, Interstate 79 and the Pennsylvania Turnpike should remain aware of changing early morning conditions, particularly in sheltered areas where temperatures can differ from nearby observations. However, the forecast does not establish widespread icy roads, freezing rain or specific highway closures.
The temperature change will be substantial compared with Friday's expected warmth. Pittsburgh is forecast to reach approximately 74 degrees Friday before temperatures fall toward 60 degrees later in the day. By early Sunday, readings near 33 degrees would represent a 41 degree difference from Friday's forecast high, spread across roughly two days rather than a sudden hourly temperature collapse.
Sunshine and Warmer Afternoons Return Next Week Despite the cold mornings, daytime conditions should improve quickly. Sunday is expected to turn sunny after the early frost, with temperatures climbing near 60 degrees. Monday will bring another sunny afternoon, with a high around 65 degrees after the morning frost risk passes.
The warming trend continues Tuesday, Oct. 20, and Wednesday, Oct. 21, when afternoon highs are expected to reach approximately 68 degrees. Overnight temperatures should moderate into the lower 40s, reducing the immediate frost concern for Pittsburgh. Thursday is also forecast to remain sunny, with a high near 68 degrees.
The available forecast does not identify another significant storm system through Thursday. Residents should continue monitoring updated National Weather Service forecasts for changes in frost coverage, minimum temperatures and any frost related advisories.
Are you preparing to protect outdoor plants from the approaching frost, or have you already started getting your home ready for colder autumn mornings?
Five Day Weather Outlook Friday 10/16: Showers and thunderstorms are expected, with precipitation chances reaching 100% and a high near 74 degrees before temperatures fall toward 60 degrees; breezy conditions and a marginal damaging wind risk accompany the cold front, with nighttime lows near 42 degrees.
Saturday 10/17: Partly sunny skies will gradually become sunny, with a high near 52 degrees and north winds of 11 to 15 mph; Saturday night turns clear and colder, with temperatures falling near 33 degrees and patchy frost developing after 1 a.m.
Sunday 10/18: Widespread frost is expected before 8 a.m., followed by sunny skies and a high near 60 degrees; Sunday night will be mostly clear, with temperatures falling near 37 degrees and another possibility of frost developing toward Monday morning.
Monday 10/19: Patchy frost is forecast before 8 a.m., followed by sunshine and a high near 65 degrees; the afternoon should be considerably warmer, while Monday night remains mostly clear with a low near 40 degrees.
Tuesday 10/20: Sunny skies and a high near 68 degrees will continue the warming trend across Pittsburgh, with no precipitation indicated in the supplied forecast; Tuesday night should remain mostly clear, with temperatures falling near 42 degrees.
Extended Weather Outlook Wednesday, Oct. 21, is expected to bring sunny skies and a high near 68 degrees. Mostly clear conditions are forecast Wednesday night, with temperatures falling near 42 degrees.
Thursday, Oct. 22, should remain sunny, with an afternoon high near 68 degrees.