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Frost dates for Phila Franklin Inst, Pennsylvania

Half of years have their last spring frost by March 30, but 1 year in 10 still frosts after April 12.

A frost date is really a percentile from 30 years of records at a nearby weather station: in about half of years a frost still comes after the median date. Both numbers are below, so you can choose the risk yourself.

The odds

Last spring frost

How often a frost still comes on or after each date.

1 year in 10
April 12
1 year in 5
April 7
3 years in 10
April 4
2 years in 5
April 1
Half of years (the median)
March 30

First fall freeze

How often the first freeze comes on or before each date.

1 year in 10
November 4
1 year in 5
November 8
3 years in 10
November 11
2 years in 5
November 14
Half of years (the median)
November 17
Growing season
about 232 days
Hardiness zone nearby
7b
Summer days
a usual high of about 31 °C87 °F
Lettuce and spinach run to seed
May to September, in hot, long days (how we know)

Summer and rain

A growing garden needs about 25 mm1 in of water a week, rain and watering together. Here is what a normal month brings.

Month by month

January
high ~5 °C42 °F · low ~-2 °C28 °F · rain ~92 mm3.6 in
February
high ~7 °C45 °F · low ~-1 °C30 °F · rain ~85 mm3.3 in
March
high ~12 °C53 °F · low ~2 °C36 °F · rain ~115 mm4.5 in
April
high ~19 °C66 °F · low ~8 °C46 °F · rain ~102 mm4 in
May
high ~24 °C76 °F · low ~14 °C56 °F · rain ~103 mm4.1 in
June
high ~29 °C85 °F · low ~19 °C66 °F · rain ~121 mm4.8 in
July
high ~32 °C89 °F · low ~22 °C71 °F · rain ~121 mm4.7 in
August
high ~31 °C87 °F · low ~21 °C69 °F · rain ~126 mm4.9 in
September
high ~27 °C80 °F · low ~17 °C63 °F · rain ~124 mm4.9 in
October
high ~20 °C68 °F · low ~11 °C51 °F · rain ~105 mm4.1 in
November
high ~14 °C56 °F · low ~5 °C41 °F · rain ~86 mm3.4 in
December
high ~8 °C47 °F · low ~1 °C33 °F · rain ~108 mm4.3 in

Where these numbers come from

NOAA NCEI 1991–2020 Climate Normals, the Phila Franklin Inst station (listed by NOAA as Phila Franklin Inst, USC00366886), at 39.96, -75.17. These are that station’s own records, unshifted. The further your garden is from it, the less exactly they describe your ground. The planner finds the nearest station to your garden and lowers its confidence with distance, so no number is presented as if it were measured in your garden.

Cold air also pools in low ground on the clear, still nights when frost happens, so a hollow can freeze while a slope a few hundred feet away does not. No table can know that about your garden. A few seasons of your own logged frosts can.

ZIP codes nearest this station

08030, 08102, 08103, 08104, 08105, 19003, 19004, 19012, 19027, 19050, 19066, 19072, 19082, 19083, 19096, 19102, 19103, 19104, 19106, 19107, 19109, 19119, 19120, 19121, 19122, 19123, 19125, 19126, 19127, 19129, 19130, 19131, 19132, 19133, 19134, 19138, 19139, 19140, 19141, 19143, 19144, 19146, 19147, 19148, 19150, 19151.

What can I plant here, and when? ›

Nearby stations

The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.

Other stations in Pennsylvania.

All locations · All plants · Folklore, checked