Frost dates for Middletown Harrisburg Intl Ap, Pennsylvania
Half of years have their last spring frost by April 9 — but 1 year in 10 still frosts after April 25.
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
- April 25
- 1 year in 5
- April 18
- 3 years in 10
- April 15
- 2 years in 5
- April 11
- Half of years (the median)
- April 9
First fall freeze
- Freeze this early in 1 year in 10
- October 18
- 1 year in 5
- October 24
- 3 years in 10
- October 27
- 2 years in 5
- October 31
- Half of years (the median)
- November 2
- Growing season
- about 206 days
- Hardiness zone nearby
- 7a
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, station Middletown Harrisburg Intl Ap (USW00014711), at 40.19, -76.76. 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
17003, 17010, 17011, 17018, 17022, 17028, 17033, 17034, 17036, 17038, 17041, 17043, 17057, 17070, 17077, 17078, 17093, 17101, 17102, 17103, 17104, 17109, 17110, 17111, 17112, 17113, 17120, 17315, 17318, 17319, 17339, 17345, 17347, 17365, 17370, 17401, 17402, 17404, 17406, 17502, 17547, 17550, 17570.
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.
- Carlisle Wtp, PA — last frost by April 23
- Lancaster Ap, PA — last frost by April 18
- Millers 4 Ne, MD — last frost by April 19
- Selinsgrove 2 S Hcn, PA — last frost by April 25
- Shippensburg, PA — last frost by April 19
- Hopewell Morgantown, PA — last frost by April 16
Other stations in Pennsylvania.
- Mahanoy City 2 N, PA — last frost by April 30
- Lehighton 1Ssw, PA — last frost by April 21
- State College Hcn, PA — last frost by April 20
- Altoona Blair Co Ap, PA — last frost by April 23
- Philadelphia Intl Ap, PA — last frost by April 2
- Willow Grove Nas, PA — last frost by April 11
- Philipsburg 2 S, PA — last frost by May 13
- Wilkes-Barre Intl Ap, PA — last frost by April 23