Frost Dates for 19018 — Secane, Pennsylvania

Half of springs at Philadelphia International Airport, PA see their last 32°F night by April 2; only one in ten is past it by March 19, and one in ten still has one after April 13. Planting tender crops after April 6 leaves a 30% risk of a frost on them, after April 8 20%, and after April 13 10%. The 11 days between the even-odds date and the one-in-ten date is narrower than at 99% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 10 in half of years, as early as October 30 one year in ten, and holds off past November 24 one year in ten. A hard freeze of 28°F follows 13 days later, around November 23; in spring the one-in-ten date for 28°F is April 3, 10 days before the 32°F one. The freeze-free season lasts 224 days in a typical year, longer than at 99% of the 176 Pennsylvania stations; it reaches 243 days one year in ten and falls short of 207 one year in ten. On average 77 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about April 13, and return around October 31. Severe cold of 16°F or below comes in 96% of winters, usually between January 4 and February 13.

July is the warmest month at Philadelphia International Airport, PA, averaging 88°F by day and 70°F at night; January is the coldest at 41°F and 26°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 58% of years.

Warmth for growing adds up to 4,047 growing degree days a year (base 50°F), more than at 98% of the 176 Pennsylvania stations. 34% of them (1,379) have built up by the end of June, and July adds the most, 890. Precipitation totals 44.2 inches a year, most in July (4.4") and least in February (2.8"); May to September bring 46% of it.

The nearest other station, Phila Franklin Inst, PA, 7 miles east of Secane, has a last frost 3 days earlier (March 30), a first frost 7 days later (November 17), a season 8 days longer.

The first measurable snow (0.1 inch or more) in Secane usually arrives around December 19, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Philadelphia International Airport, PA, 5.1 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 12 days after the last snow.

ZIP 19018 is 5 miles from Philadelphia International Airport, PA, which stands at 10 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 27 other ZIP codes share the station; its figures are presented in full for 08096 (Woodbury). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19018 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.