West Middlesex, PA 16143 Frost Dates
16143, near West Middlesex, PA: the frost window
The last spring frost here typically falls around 05/15, about 260 days from today. Fall's first freeze usually shows up around 10/03, roughly 140 days after the last spring frost.
Zone 6a (-10 to -5°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for West Middlesex, not a forecast for this year.
Stretching the season past the first frost
West Middlesex's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
05/15 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/01 and only about 1 year in 10 sees frost after that.
West Middlesex against the rest of the dataset
About 140 days separate West Middlesex's last and first frost, putting it 37,088 of 40,283 ZIP codes nationally. Within PA, it ranks 1,998 of 2,088.
Learn more
Two guides worth reading on 16143: zone vs. frost date, on why Zone 6a and West Middlesex's frost date answer different questions, and the frost range, on how to read the range around West Middlesex's dates instead of trusting one.