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.
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
- 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
How often the first freeze comes on or before each date.
- 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 zone nearby
- 6a
- Summer days
- a usual high of about 28 °C82 °F
- Lettuce and spinach run to seed
- June 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 ~3 °C37 °F · low ~-7 °C19 °F · rain ~92 mm3.6 in
- February
- high ~5 °C40 °F · low ~-7 °C20 °F · rain ~87 mm3.4 in
- March
- high ~10 °C49 °F · low ~-3 °C27 °F · rain ~99 mm3.9 in
- April
- high ~17 °C63 °F · low ~2 °C36 °F · rain ~103 mm4 in
- May
- high ~22 °C72 °F · low ~8 °C47 °F · rain ~125 mm4.9 in
- June
- high ~27 °C80 °F · low ~13 °C56 °F · rain ~123 mm4.9 in
- July
- high ~29 °C83 °F · low ~15 °C60 °F · rain ~115 mm4.5 in
- August
- high ~28 °C82 °F · low ~15 °C59 °F · rain ~102 mm4 in
- September
- high ~24 °C76 °F · low ~11 °C52 °F · rain ~101 mm4 in
- October
- high ~18 °C64 °F · low ~4 °C40 °F · rain ~85 mm3.4 in
- November
- high ~11 °C52 °F · low ~-1 °C30 °F · rain ~78 mm3.1 in
- December
- high ~5 °C41 °F · low ~-4 °C24 °F · rain ~89 mm3.5 in
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Confluence 1 SW Dam station (listed by NOAA as 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 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
15411, 15424, 15459, 15540, 15551, 15557, 21531.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Lake Lynn, WV, last frost by April 25
- Cumberland 2, MD, last frost by April 15
- Charleroi Lock, PA, last frost by April 13
- Johnstown Cambria County Airport, 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 County Airport, PA, last frost by April 23
- Prince Gallitzin State Park, 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, PA, last frost by April 20
When do I plant? · Where the dates come from
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