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.
Every other site gives you one date. A frost date is not a date: it is a percentile from 30 years of records at a nearby weather station, and planting to the median means losing the crop in half of years. Both numbers are below, so you can choose the risk yourself.
The odds
Last spring frost
- Frost this late in 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
- Freeze this early in 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
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, station 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 resolves the nearest station to your own ZIP and lowers its confidence with distance, rather than presenting one number as if it were measured in your yard.
Cold air also pools in low ground on the clear, still nights when frost happens, so a hollow can freeze while a slope a hundred metres away does not. No table can know that about your garden. Your own logged frosts eventually can.
ZIP codes nearest this station
16020, 16035, 16038, 16057, 16061, 16105, 16113, 16114, 16116, 16121, 16124, 16125, 16127, 16133, 16137, 16140, 16142, 16143, 16146, 16148, 16150, 16153, 16154, 16155, 16156, 16159, 16161, 44436.
What can I plant here, and when? →
Nearby stations
The nearest stations, and how their last-frost dates compare — the frost gradient across your area, which no single station shows.
- Franklin Hcn, PA — last frost by May 2
- Mosquito Creek Lake, OH — last frost by April 30
- Beaver Falls 1 Ne, PA — last frost by April 27
- Millport 4 Ne Hcn, OH — last frost by May 2
- Schenley Lock, PA — last frost by April 21
- Putneyville 2 Se Dam, PA — last frost by May 10
Other stations in Pennsylvania.
- Erie Intl Ap Hcn, PA — last frost by April 26
- Mckeesport, PA — last frost by May 2
- Washington 3 Ne, PA — last frost by April 24
- Laurel Mtn, PA — last frost by April 26
- Prince Gallitzin Sp, PA — last frost by May 10
- Johnstown Cambria Co Ap, 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