Safe Harbor Dam, Pennsylvania climate: Climate normals at a NOAA weather station
Safe Harbor Dam's normal year runs from 25°F January nights to 87°F July afternoons, with 46.3 inches of precipitation and 21 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.6°C, January lows of −4°C, July highs of 30°C, 1,176 mm of precipitation a year.
- NOAA stationSafe Harbor Dam
- Station IDUSC00367732
- Location39.93°N 76.39°W
- Elevation195 ft (59 m)
On October 23, the normal high in Safe Harbor Dam is 62°F and the normal low 46°F, and the chance of measurable rain or snow is 30%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Safe Harbor Dam.
- Jan 39° 25°
- Feb 41° 26°
- Mar 50° 33°
- Apr 63° 44°
- May 72° 53°
- Jun 82° 63°
- Jul 87° 68°
- Aug 84° 66°
- Sep 77° 60°
- Oct 65° 48°
- Nov 53° 38°
- Dec 44° 30°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Safe Harbor Dam each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 25°F. The most precipitation falls in September (4.88 in), the least in February (2.68 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 39°F | 25°F | 32.0°F | 3.26 | 6.1 | 11 | <1 | 24 | 9 h 40 min |
| February | 41°F | 26°F | 33.9°F | 2.68 | 7.6 | 10 | <1 | 22 | 10 h 40 min |
| March | 50°F | 33°F | 41.2°F | 4.05 | 3.5 | 11 | <1 | 15 | 11 h 50 min |
| April | 63°F | 44°F | 53.3°F | 3.54 | 0.0 | 12 | <1 | 2 | 13 h 10 min |
| May | 72°F | 53°F | 62.8°F | 3.88 | 0.0 | 13 | 1 | <1 | 14 h 20 min |
| June | 82°F | 63°F | 72.5°F | 4.55 | 0.0 | 11 | 4 | <1 | 15 h |
| July | 87°F | 68°F | 77.3°F | 4.31 | 0.0 | 11 | 10 | <1 | 14 h 50 min |
| August | 84°F | 66°F | 75.3°F | 3.57 | 0.0 | 10 | 5 | <1 | 13 h 50 min |
| September | 77°F | 60°F | 68.3°F | 4.88 | 0.0 | 9 | 1 | <1 | 12 h 30 min |
| October | 65°F | 48°F | 56.5°F | 4.37 | 0.0 | 10 | <1 | <1 | 11 h 10 min |
| November | 53°F | 38°F | 45.5°F | 3.40 | 0.5 | 9 | <1 | 6 | 10 h |
| December | 44°F | 30°F | 36.9°F | 3.82 | 3.6 | 11 | <1 | 19 | 9 h 20 min |
| Year (annual) | 63°F | 46°F | 54.6°F | 46.31 | 21.3 | 126 | 20 | 87 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −4°C | 0.0°C | 83 mm | 15 cm |
| February | 5°C | −3°C | 1.1°C | 68 mm | 19 cm |
| March | 10°C | 1°C | 5.1°C | 103 mm | 9 cm |
| April | 17°C | 7°C | 11.8°C | 90 mm | 0 cm |
| May | 22°C | 12°C | 17.1°C | 99 mm | 0 cm |
| June | 28°C | 17°C | 22.5°C | 116 mm | 0 cm |
| July | 30°C | 20°C | 25.2°C | 109 mm | 0 cm |
| August | 29°C | 19°C | 24.1°C | 91 mm | 0 cm |
| September | 25°C | 15°C | 20.2°C | 124 mm | 0 cm |
| October | 18°C | 9°C | 13.6°C | 111 mm | 0 cm |
| November | 12°C | 3°C | 7.5°C | 86 mm | 1 cm |
| December | 6°C | −1°C | 2.7°C | 97 mm | 9 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00367732; 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.
Which months are mildest at Safe Harbor Dam?
Normal highs sit between 65°F and 85°F in May, June, August and September. Of those, September has the fewest days with rain (9).
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 USC00367732.
When is the last frost at Safe Harbor Dam?
In Safe Harbor Dam, the last spring frost (32°F) comes after April 1 in half of years and after April 13 in one year in ten; the first autumn frost comes before November 10 in half of years and before October 28 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
- April 11 year in 10 after April 13; 9 in 10 after March 18
- First autumn frost, half of years before
- November 101 year in 10 before October 28; 9 in 10 before November 25
NOAA puts the median frost-free season at 221 days, and the season without a hard freeze (28°F) at 244 days.
A hard freeze (28°F) comes after March 22 in half of springs and before November 22 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Safe Harbor Dam in zone 7a in ZIP code 17516, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 7b: the coldest night of a typical year reaches 9°F (19 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Pennsylvania · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00367732; 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 at Safe Harbor Dam?
In a normal year in Safe Harbor Dam, 20 days a year reach 90°F, 87 nights fall to 32°F or colder and 126 days bring measurable precipitation.
- Days at 90°F or more
- 20a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 87a normal year
- Days that stay below freezing
- 18high of 32°F or less
- Days with 0.01 inch of precipitation
- 126a normal year
- Days with 1 inch of snow or more
- 6a normal year
The highest temperature in this station's record (since 1995) is 105°F, on July 23, 2011; the lowest is 1°F, on February 6, 1996.
The wettest calendar year on that record is 2018, with 68.36 in; the snowiest season is 2009–10, with 57.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00367732; records: ACIS (NOAA Regional Climate Centers), station USC00367732. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Safe Harbor Dam?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds at Safe Harbor Dam, 4.0 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (67%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 2.0 |
| February | 69% | 2.9 |
| March | 68% | 3.8 |
| April | 72% | 5.0 |
| May | 72% | 5.5 |
| June | 78% | 6.2 |
| July | 82% | 6.2 |
| August | 80% | 5.4 |
| September | 76% | 4.3 |
| October | 72% | 3.2 |
| November | 73% | 2.3 |
| December | 67% | 1.8 |
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 many heating and cooling degree days does Safe Harbor Dam record?
A normal year at Safe Harbor Dam brings 4,908 heating degree days, 9% fewer than the median U.S. place (5,373), and 1,164 cooling degree days, 28% more than the median (908). Six months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,703 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,021 | 0 |
| February | 871 | 0 |
| March | 736 | 0 |
| April | 361 | 12 |
| May | 130 | 60 |
| June | 12 | 237 |
| July | 0 | 380 |
| August | 1 | 320 |
| September | 40 | 139 |
| October | 280 | 16 |
| November | 585 | 0 |
| December | 871 | 0 |
| Year (annual) | 4,908 | 1,164 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00367732. 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.
Have recent years at Safe Harbor Dam been warmer than normal?
2025 averaged 54.7°F, 0.1°F above the 1991-2020 normal of 54.6°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 56.1°F | +1.5°F | 49.99 | – |
| 2022 | 54.9°F | +0.3°F | 52.35 | 13.7 |
| 2023 | 56.5°F | +1.9°F | 42.02 | 3.6 |
| 2024 | 56.7°F | +2.1°F | 43.36 | 23.1 |
| 2025 | 54.7°F | +0.1°F | 43.88 | 17.6 |
Source: observed years: ACIS, station USC00367732. A year counts only with all twelve months complete.
How does Safe Harbor Dam's climate compare?
Safe Harbor Dam is warmer than 104 of the 108 places with their own NOAA record in Pennsylvania, and wetter than 69. Across the 7,247 U.S. stations with normals, its annual mean of 54.6°F is warmer than 59%.
In the Köppen classification computed from these normals, Safe Harbor Dam is Cfa: temperate, no dry season, hot 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 Safe Harbor Dam share this climate record?
9 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.
- Willow Street, PA10,010 people · 7 mi NE
- Millersville, PA9,290 people · 6 mi N
- Jarrettsville, MD2,629 people · 23 mi S
- Lampeter, PA2,094 people · 9 mi NE
- Conestoga, PA1,174 people · 3 mi E
- East Prospect, PA962 people · 8 mi NW
- Pylesville, MD806 people · 16 mi S
- Washington Boro, PA655 people · 7 mi NW
- Refton, PA589 people · 8 mi E
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 Safe Harbor Dam's climate
What is the coldest month at Safe Harbor Dam?
January, with a normal high of 39°F and a normal low of 25°F. The warmest is July (87°F by day, 68°F at night).
Does it snow at Safe Harbor Dam?
Yes: 21 inches in a normal year, falling on 9 days with 0.1 inch or more, the most in February (7.6 inches).
What is the rainiest month at Safe Harbor Dam?
September, with 4.88 in of precipitation in a normal year; the driest is February with 2.68 in.
What plant hardiness zone is Safe Harbor Dam in?
The USDA's 2023 map puts Safe Harbor Dam in zone 7a in ZIP code 17516, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches 9°F (19 years, 1991-2020): zone 7b.
How late can frost come at Safe Harbor Dam?
In half of years the last 32°F night comes after April 1; in one year in ten it comes after April 13. Waiting until April 13 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Pennsylvania climateThe statewide normals and every place in the state
- Landisville, PA14 miles from this station, 51.1°F a year
- Lancaster, PA14 miles from this station, 53.3°F a year
- York 3 SSW Pump Station, PA19 miles from this station, 54.0°F a year
- New Holland, PA20 miles from this station, 54.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made