Frost dates for Mercer, Pennsylvania
Half of years have their last spring frost by May 15, but 1 year in 10 still frosts after June 1.
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
- June 1
- 1 year in 5
- May 27
- 3 years in 10
- May 23
- 2 years in 5
- May 19
- Half of years (the median)
- May 15
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- September 19
- 1 year in 5
- September 24
- 3 years in 10
- September 28
- 2 years in 5
- October 1
- Half of years (the median)
- October 3
- Growing season
- about 140 days
- Hardiness zone nearby
- 6a
- Summer days
- a usual high of about 27 °C81 °F
- Lettuce and spinach run to seed
- June to September, in hot, long days (how we know)
Summer heat
Month by month
- January
- high ~2 °C35 °F · low ~-9 °C16 °F
- February
- high ~4 °C38 °F · low ~-8 °C17 °F
- March
- high ~9 °C48 °F · low ~-4 °C25 °F
- April
- high ~16 °C62 °F · low ~1 °C34 °F
- May
- high ~22 °C71 °F · low ~7 °C44 °F
- June
- high ~26 °C79 °F · low ~12 °C53 °F
- July
- high ~28 °C82 °F · low ~14 °C56 °F
- August
- high ~28 °C82 °F · low ~13 °C56 °F
- September
- high ~24 °C75 °F · low ~9 °C49 °F
- October
- high ~17 °C63 °F · low ~3 °C38 °F
- November
- high ~10 °C50 °F · low ~-2 °C29 °F
- December
- high ~4 °C40 °F · low ~-6 °C21 °F
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Mercer station (listed by NOAA as Mercer, USC00365651), at 41.22, -80.23. 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
16020, 16035, 16038, 16113, 16114, 16124, 16125, 16127, 16133, 16137, 16142, 16148…
+2 moreShow fewer
16153, 16154.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Franklin, PA, last frost by May 2
- Beaver Falls 1 NE, PA, last frost by April 27
- Millport 4 NE, OH, last frost by May 2
- Schenley Lock, PA, last frost by April 21
- Putneyville 2 SE Dam, PA, last frost by May 10
- Ravenna 2 S, OH, last frost by April 21
Other stations in Pennsylvania.
- Erie International Airport, PA, last frost by April 26
- Mckeesport, PA, last frost by May 2
- Washington 3 NE, PA, last frost by April 24
- Charleroi Lock, PA, last frost by April 13
- Prince Gallitzin State Park, PA, last frost by May 10
- Johnstown Cambria County Airport, PA, last frost by April 29
- Philipsburg 2 S, PA, last frost by May 13
- Confluence 1 SW Dam, PA, last frost by April 30
When do I plant? · Where the dates come from
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