Slippery Rock, Pennsylvania climate: Normal weather by month, frost dates and records
Slippery Rock's normal year runs from 17°F January nights to 81°F July afternoons, with 45.2 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.9°C, January lows of −8°C, July highs of 27°C, 1,149 mm of precipitation a year.
- NOAA stationSlippery Rock (1 mi SSW)
- Station IDUSC00368184
- Location41.06°N 80.06°W
- Elevation1,260 ft (384 m)
- Population3,558
On October 23, the normal high in Slippery Rock is 59°F and the normal low 37°F, and the chance of measurable rain or snow is 44%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Slippery Rock.
- Jan 33° 17°
- Feb 37° 18°
- Mar 46° 25°
- Apr 59° 35°
- May 69° 45°
- Jun 77° 54°
- Jul 81° 58°
- Aug 80° 56°
- Sep 74° 50°
- Oct 62° 39°
- Nov 49° 31°
- Dec 38° 23°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Slippery Rock each month?
July is the warmest month, with normal highs of 81°F; January the coldest, with normal lows of 17°F. The most precipitation falls in June (4.76 in), the least in February (2.69 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 33°F | 17°F | 25.1°F | 3.47 | 17 | <1 | 27 | 9 h 30 min |
| February | 37°F | 18°F | 27.4°F | 2.69 | 14 | <1 | 25 | 10 h 40 min |
| March | 46°F | 25°F | 35.5°F | 3.41 | 13 | <1 | 23 | 11 h 50 min |
| April | 59°F | 35°F | 46.7°F | 3.94 | 14 | <1 | 12 | 13 h 20 min |
| May | 69°F | 45°F | 57.1°F | 4.14 | 15 | 1 | 3 | 14 h 30 min |
| June | 77°F | 54°F | 65.3°F | 4.76 | 14 | 2 | <1 | 15 h 10 min |
| July | 81°F | 58°F | 69.7°F | 4.63 | 13 | 6 | <1 | 14 h 50 min |
| August | 80°F | 56°F | 68.2°F | 4.02 | 11 | 4 | <1 | 13 h 50 min |
| September | 74°F | 50°F | 61.8°F | 4.07 | 11 | 1 | <1 | 12 h 30 min |
| October | 62°F | 39°F | 50.5°F | 3.45 | 14 | <1 | 7 | 11 h 10 min |
| November | 49°F | 31°F | 39.7°F | 3.47 | 13 | <1 | 18 | 10 h |
| December | 38°F | 23°F | 30.6°F | 3.19 | 15 | <1 | 25 | 9 h 10 min |
| Year (annual) | 59°F | 38°F | 48.1°F | 45.24 | 164 | 13 | 142 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 1°C | −8°C | −3.8°C | 88 mm |
| February | 3°C | −8°C | −2.6°C | 68 mm |
| March | 8°C | −4°C | 1.9°C | 87 mm |
| April | 15°C | 2°C | 8.2°C | 100 mm |
| May | 21°C | 7°C | 13.9°C | 105 mm |
| June | 25°C | 12°C | 18.5°C | 121 mm |
| July | 27°C | 14°C | 20.9°C | 118 mm |
| August | 27°C | 14°C | 20.1°C | 102 mm |
| September | 23°C | 10°C | 16.6°C | 103 mm |
| October | 16°C | 4°C | 10.3°C | 88 mm |
| November | 9°C | −1°C | 4.3°C | 88 mm |
| December | 3°C | −5°C | −0.8°C | 81 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, New Castle (16 miles away), gets 28 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00368184; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Slippery Rock?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (11).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00368184.
When is the last frost in Slippery Rock?
In Slippery Rock, the last spring frost (32°F) comes after May 7 in half of years and after May 25 in one year in ten; the first autumn frost comes before October 14 in half of years and before October 1 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 71 year in 10 after May 25; 9 in 10 after April 22
- First autumn frost, half of years before
- October 141 year in 10 before October 1; 9 in 10 before October 30
NOAA puts the median frost-free season at 158 days, and the season without a hard freeze (28°F) at 183 days.
A hard freeze (28°F) comes after April 26 in half of springs and before October 27 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Slippery Rock in zone 6a in ZIP code 16057, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Slippery Rock's NOAA station is in zone 6a: the coldest night of a typical year reaches −7°F (26 complete years).
Frost dates for every NOAA station in Pennsylvania · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00368184; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Slippery Rock?
In a normal year in Slippery Rock, 13 days a year reach 90°F, 142 nights fall to 32°F or colder and 164 days bring measurable precipitation.
- Days at 90°F or more
- 13a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 142a normal year
- Days that stay below freezing
- 31high of 32°F or less
- Days with 0.01 inch of precipitation
- 164a normal year
The highest temperature in this station's record (since 1949) is 102°F, on July 16, 1988; the lowest is −28°F, on January 19, 1994.
The wettest calendar year on that record is 2018, with 56.35 in; the snowiest season is 1959–60, with 72.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00368184; records: ACIS (NOAA Regional Climate Centers), station USC00368184. Records use complete months only; a month missing more than three days is left out.
How sunny is Slippery Rock?
Over a year 68% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Slippery Rock, 3.6 kWh per square metre a day. July is the sunniest month (77%) and December the cloudiest (47%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 51% | 1.4 |
| February | 57% | 2.3 |
| March | 60% | 3.3 |
| April | 65% | 4.5 |
| May | 69% | 5.3 |
| June | 74% | 5.9 |
| July | 77% | 5.9 |
| August | 77% | 5.2 |
| September | 74% | 4.2 |
| October | 64% | 2.7 |
| November | 61% | 1.8 |
| December | 47% | 1.1 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Slippery Rock need?
A normal year in Slippery Rock brings 6,575 heating degree days, 22% more than the median U.S. place (5,373), and 454 cooling degree days, 50% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,473 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,237 | 0 |
| February | 1,054 | 0 |
| March | 915 | 0 |
| April | 553 | 2 |
| May | 272 | 27 |
| June | 78 | 85 |
| July | 17 | 161 |
| August | 29 | 128 |
| September | 143 | 45 |
| October | 456 | 5 |
| November | 758 | 0 |
| December | 1,065 | 0 |
| Year (annual) | 6,575 | 454 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00368184. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Slippery Rock been warmer than normal lately?
2023 averaged 51.1°F, 3.0°F above the 1991-2020 normal of 48.1°F.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2023 | 51.1°F | +3.0°F | 40.68 |
Over 57 complete years from 1951 to 2023, the station's annual mean temperature rose at a fitted 2.6°F per century (+0.14°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00368184; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Slippery Rock's climate compare?
Slippery Rock is warmer than 26 of the other 107 places with their own NOAA record in Pennsylvania, and wetter than 65. Across the 7,247 U.S. stations with normals, its annual mean of 48.1°F is warmer than 32%.
In the Köppen classification computed from these normals, Slippery Rock is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Slippery Rock share this climate record?
16 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Grove City, PA7,749 people · 7 mi N
- Slippery Rock University, PA2,724 people · 1 mi NE
- Harrisville, PA792 people · 6 mi NE
- Lake Arthur Estates, PA450 people · 8 mi SW
- Clintonville, PA429 people · 14 mi NE
- Bruin, PA402 people · 17 mi E
- Harlansburg, PA325 people · 7 mi W
- West Liberty, PA323 people · 3 mi S
- Eau Claire, PA295 people · 15 mi E
- Forestville, PA280 people · 4 mi NE
- Portersville, PA225 people · 10 mi SW
- Barkeyville, PA184 people · 11 mi N
- North Washington, PA178 people · 13 mi E
- West Sunbury, PA176 people · 9 mi E
- Boyers, PA155 people · 9 mi NE
- Cherry Valley, PA57 people · 15 mi NE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Slippery Rock's climate
What is the coldest month in Slippery Rock?
January, with a normal high of 33°F and a normal low of 17°F. The warmest is July (81°F by day, 58°F at night).
Does it snow in Slippery Rock?
Yes. NOAA publishes no 1991-2020 snowfall normal for Slippery Rock's NOAA station; the nearest record that keeps one, New Castle (16 miles away), records 28 inches of snow in a normal year.
What is the rainiest month in Slippery Rock?
June, with 4.76 in of precipitation in a normal year; the driest is February with 2.69 in.
What plant hardiness zone is Slippery Rock in?
The USDA's 2023 map puts Slippery Rock in zone 6a in ZIP code 16057, the nearest ZIP area. By the same method at Slippery Rock's NOAA station, the coldest night of a typical year reaches −7°F (26 years, 1991-2020): zone 6a.
How late can frost come in Slippery Rock?
In half of years the last 32°F night comes after May 7; in one year in ten it comes after May 25. Waiting until May 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Pennsylvania climateThe statewide normals and every place in the state
- Mercer, PA15 miles from this station, 48.5°F a year
- New Castle, PA16 miles from this station, 51.1°F a year
- Butler, PA17 miles from this station, 48.5°F a year
- Beaver Falls, PA24 miles from this station, 50.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made