Frost dates for Confluence 1 Sw Dam, Pennsylvania
Half of years have their last spring frost by April 30 — but 1 year in 10 still frosts after May 18.
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
- May 18
- 1 year in 5
- May 11
- 3 years in 10
- May 6
- 2 years in 5
- May 2
- Half of years (the median)
- April 30
First fall freeze
- Freeze this early in 1 year in 10
- October 4
- 1 year in 5
- October 7
- 3 years in 10
- October 12
- 2 years in 5
- October 15
- Half of years (the median)
- October 18
- Growing season
- about 171 days
- Hardiness zones nearby
- 6a, 6b
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, station Confluence 1 Sw Dam (USC00361705), at 39.80, -79.37. 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
15411, 15421, 15424, 15425, 15430, 15431, 15437, 15446, 15455, 15456, 15459, 15464, 15469, 15470, 15532, 15540, 15542, 15551, 15557, 15558, 15562, 21520, 21522, 21531, 21536, 21541.
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.
- Lake Lynn, WV — last frost by April 25
- Laurel Mtn, PA — last frost by April 26
- Cumberland 2 Hcn, MD — last frost by April 15
- Johnstown Cambria Co Ap, PA — last frost by April 29
- Mckeesport, PA — last frost by May 2
- Washington 3 Ne, PA — last frost by April 24
Other stations in Pennsylvania.
- Schenley Lock, PA — last frost by April 21
- Altoona Blair Co Ap, PA — last frost by April 23
- Prince Gallitzin Sp, PA — last frost by May 10
- Putneyville 2 Se Dam, PA — last frost by May 10
- Beaver Falls 1 Ne, PA — last frost by April 27
- Philipsburg 2 S, PA — last frost by May 13
- Shippensburg, PA — last frost by April 19
- State College Hcn, PA — last frost by April 20