Final Frost of the Season Expected Across Pennsylvania and the Mid-Atlantic Tuesday Morning May 12 With Temperatures Dropping Into the Low to Mid 30s Before Warming Trend Allows Planting
MID-ATLANTIC — What forecasters are calling potentially the final frost of the season is expected across Pennsylvania and the broader Mid-Atlantic region on Tuesday morning, May 12, 2026, with GFS model data valid at 10z Tuesday showing widespread temperatures in the low to mid 30s across interior Pennsylvania and surrounding areas. Temperatures as low as 28 to 30 degrees are forecast across the coldest interior zones, with readings climbing into the 40s closer to the coast and urban corridors. After this final frost event clears Tuesday morning, gardeners and planters are being given the green light to commence outdoor planting.
Temperatures Dropping Into the Low 30s Across Interior Pennsylvania Tuesday Morning
GFS model data initialized at 6z May 11 and valid Tuesday morning shows the coldest temperatures concentrated across interior Pennsylvania, with readings of 30 to 37 degrees widespread through the region. The coldest pockets are showing temperatures as low as 28 to 30 degrees across the highest and most exposed interior locations well away from urban heat influences.
Areas including central and western Pennsylvania are sitting inside the deepest cold zone on Tuesday morning, with temperatures cold enough to damage or kill unprotected tender plants, seedlings, and newly established garden growth.
Coastal and Urban Areas Running Warmer in the 40s Providing Some Frost Protection
Coastal New Jersey and the Delaware and Maryland shoreline zones are running significantly warmer than the interior, with temperatures holding in the low to mid 40s through Tuesday morning. The urban heat island effect and proximity to the relatively warmer ocean waters are providing meaningful frost protection for coastal and densely populated areas compared to the frigid interior zones.
Readings of 43 to 48 degrees along the immediate coast and in urban corridors keep those areas above the frost threshold even during the coldest hours of Tuesday morning.
Final Frost Clears Tuesday Opening the Green Light for Outdoor Planting Season
Forecasters are expressing confidence that Tuesday morning’s frost event represents the final frost of the 2026 season across Pennsylvania and the Mid-Atlantic region. Once this cold snap clears through Tuesday morning, warming temperatures through the remainder of May are expected to make outdoor planting safe and sustainable for gardeners across the entire region.
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