Williamsport, Pennsylvania climate: Normal weather by month, frost dates and records
Williamsport's normal year runs from 20°F January nights to 85°F July afternoons, with 43.5 inches of precipitation and 36 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 10.7°C, January lows of −7°C, July highs of 29°C, 1,105 mm of precipitation a year.
- NOAA stationWilliamsport Regional Airport
- Station IDUSW00014778
- Location41.24°N 76.92°W
- Elevation520 ft (159 m)
- Population27,628
On October 23, the normal high in Williamsport is 60°F and the normal low 40°F, and the chance of measurable rain or snow is 34%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Williamsport.
- Jan 35° 20°
- Feb 39° 22°
- Mar 48° 29°
- Apr 62° 39°
- May 72° 49°
- Jun 81° 58°
- Jul 85° 63°
- Aug 83° 61°
- Sep 75° 54°
- Oct 63° 43°
- Nov 51° 33°
- Dec 40° 26°
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 Williamsport each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 20°F. The most precipitation falls in September (4.76 in), the least in February (2.31 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 35°F | 20°F | 27.7°F | 2.96 | 9.7 | 12 | <1 | 27 | 9 h 30 min |
| February | 39°F | 22°F | 30.1°F | 2.31 | 9.3 | 10 | <1 | 25 | 10 h 40 min |
| March | 48°F | 29°F | 38.7°F | 3.13 | 7.3 | 12 | <1 | 21 | 11 h 50 min |
| April | 62°F | 39°F | 50.3°F | 3.62 | 0.8 | 12 | <1 | 7 | 13 h 20 min |
| May | 72°F | 49°F | 60.8°F | 3.86 | 0.0 | 14 | 2 | 1 | 14 h 30 min |
| June | 81°F | 58°F | 69.4°F | 3.85 | 0.0 | 12 | 3 | <1 | 15 h 10 min |
| July | 85°F | 63°F | 73.7°F | 4.64 | 0.0 | 12 | 7 | <1 | 14 h 50 min |
| August | 83°F | 61°F | 72.0°F | 4.17 | 0.0 | 11 | 4 | <1 | 13 h 50 min |
| September | 75°F | 54°F | 64.7°F | 4.76 | 0.0 | 10 | 1 | <1 | 12 h 30 min |
| October | 63°F | 43°F | 53.0°F | 3.70 | 0.1 | 11 | <1 | 3 | 11 h 10 min |
| November | 51°F | 33°F | 41.9°F | 3.25 | 1.7 | 10 | <1 | 15 | 9 h 50 min |
| December | 40°F | 26°F | 32.8°F | 3.27 | 6.9 | 12 | <1 | 24 | 9 h 10 min |
| Year (annual) | 61°F | 41°F | 51.2°F | 43.52 | 35.8 | 137 | 17 | 122 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 2°C | −7°C | −2.4°C | 75 mm | 25 cm |
| February | 4°C | −6°C | −1.1°C | 59 mm | 24 cm |
| March | 9°C | −2°C | 3.7°C | 80 mm | 19 cm |
| April | 17°C | 4°C | 10.2°C | 92 mm | 2 cm |
| May | 22°C | 10°C | 16.0°C | 98 mm | 0 cm |
| June | 27°C | 15°C | 20.8°C | 98 mm | 0 cm |
| July | 29°C | 17°C | 23.2°C | 118 mm | 0 cm |
| August | 28°C | 16°C | 22.2°C | 106 mm | 0 cm |
| September | 24°C | 12°C | 18.2°C | 121 mm | 0 cm |
| October | 17°C | 6°C | 11.7°C | 94 mm | 0 cm |
| November | 10°C | 1°C | 5.5°C | 83 mm | 4 cm |
| December | 4°C | −3°C | 0.4°C | 83 mm | 18 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014778; 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 Williamsport?
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 (10).
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 USW00014778.
When is the last frost in Williamsport?
In Williamsport, the last spring frost (32°F) comes after April 24 in half of years and after May 11 in one year in ten; the first autumn frost comes before October 23 in half of years and before October 6 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 241 year in 10 after May 11; 9 in 10 after April 12
- First autumn frost, half of years before
- October 231 year in 10 before October 6; 9 in 10 before November 5
NOAA puts the median frost-free season at 180 days, and the season without a hard freeze (28°F) at 205 days.
A hard freeze (28°F) comes after April 12 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Williamsport in zone 6b in ZIP code 17702, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Williamsport's NOAA station is in zone 6b: the coldest night of a typical year reaches −1°F (30 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 USW00014778; 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 Williamsport?
In a normal year in Williamsport, 17 days a year reach 90°F, 122 nights fall to 32°F or colder and 137 days bring measurable precipitation.
- Days at 90°F or more
- 17a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 122a normal year
- Days that stay below freezing
- 27high of 32°F or less
- Days with 0.01 inch of precipitation
- 137a normal year
- Days with 1 inch of snow or more
- 10a normal year
The highest temperature in Williamsport's official record (kept by the National Weather Service since 1895) is 106°F, on July 9, 1936; the lowest is −20°F, on January 21, 1994.
The wettest calendar year on that record is 2011, with 70.26 in; the snowiest season is 1995–96, with 85.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014778; records: ACIS (NOAA Regional Climate Centers), NWS threaded record IPTthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Williamsport, and how clear are its skies?
The summer (June-August) dew point averages 61°F. The muggiest month is July, with an average dew point of 62°F; the driest air comes in January (18°F). February is the windiest month (7.8 mph on average), and June has the most clear or nearly clear hours (55%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 18°F | 65% | 51% | 7.1 mph | 40% | 45% |
| February | 21°F | 62% | 47% | 7.8 mph | 41% | 45% |
| March | 30°F | 58% | 40% | 7.6 mph | 46% | 40% |
| April | 40°F | 59% | 40% | 6.8 mph | 50% | 30% |
| May | 53°F | 68% | 47% | 5.7 mph | 48% | 26% |
| June | 61°F | 69% | 48% | 5.2 mph | 55% | 16% |
| July | 62°F | 71% | 49% | 4.7 mph | 51% | 21% |
| August | 60°F | 74% | 50% | 4.4 mph | 54% | 24% |
| September | 50°F | 76% | 53% | 5.0 mph | 51% | 29% |
| October | 37°F | 69% | 49% | 6.1 mph | 47% | 37% |
| November | 29°F | 70% | 56% | 6.9 mph | 37% | 47% |
| December | 21°F | 69% | 57% | 7.0 mph | 36% | 50% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014778. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Williamsport?
Over a year 69% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Williamsport, 3.7 kWh per square metre a day. July is the sunniest month (76%) and December the cloudiest (55%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 59% | 1.7 |
| February | 63% | 2.5 |
| March | 64% | 3.5 |
| April | 66% | 4.6 |
| May | 68% | 5.3 |
| June | 72% | 5.8 |
| July | 76% | 5.9 |
| August | 75% | 5.1 |
| September | 72% | 4.1 |
| October | 65% | 2.7 |
| November | 64% | 1.9 |
| December | 55% | 1.3 |
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 Williamsport need?
A normal year in Williamsport brings 5,774 heating degree days, 7% more than the median U.S. place (5,373), and 796 cooling degree days, 12% 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 3,083 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,156 | 0 |
| February | 977 | 0 |
| March | 815 | 0 |
| April | 445 | 6 |
| May | 180 | 48 |
| June | 28 | 160 |
| July | 2 | 273 |
| August | 6 | 222 |
| September | 90 | 80 |
| October | 382 | 9 |
| November | 693 | 0 |
| December | 1,000 | 0 |
| Year (annual) | 5,774 | 796 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014778. 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 Williamsport been warmer than normal lately?
2025 averaged 52.1°F, 0.9°F above the 1991-2020 normal of 51.2°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 53.3°F | +2.0°F | 44.69 | 31.9 |
| 2022 | 52.0°F | +0.8°F | 40.96 | 35.3 |
| 2023 | 53.9°F | +2.7°F | 45.99 | 12.0 |
| 2024 | 54.3°F | +3.1°F | 43.86 | 24.7 |
| 2025 | 52.1°F | +0.9°F | 35.77 | 12.4 |
Over 120 complete years from 1874 to 2025, 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 USW00014778; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Williamsport's climate compare?
Williamsport is warmer than 62 of the other 107 places with their own NOAA record in Pennsylvania, and wetter than 45. Across the 7,247 U.S. stations with normals, its annual mean of 51.2°F is warmer than 46%.
In the Köppen classification computed from these normals, Williamsport is Dfa: continental, 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 Williamsport share this climate record?
12 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.
- South Williamsport, PA6,176 people · 4 mi W
- Kenmar, PA4,937 people · 2 mi NW
- Montoursville, PA4,678 people · 0 mi NE
- Garden View, PA2,510 people · 7 mi W
- Muncy, PA2,405 people · 8 mi E
- Hughesville, PA2,120 people · 10 mi E
- Montgomery, PA1,548 people · 6 mi SE
- Dewart, PA1,241 people · 10 mi S
- Duboistown, PA1,186 people · 6 mi W
- Faxon, PA834 people · 3 mi W
- Picture Rocks, PA632 people · 11 mi E
- Allenwood, PA354 people · 9 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Williamsport's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Williamsport. This page uses Williamsport Regional Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Williamsport 2 USC00369735 | 3 mi W | 525 ft | 51.8°F | 21°F | 86°F | 42.7 | 33 | April 25 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Williamsport's climate
What is the coldest month in Williamsport?
January, with a normal high of 35°F and a normal low of 20°F. The warmest is July (85°F by day, 63°F at night).
Does it snow in Williamsport?
Yes: 36 inches in a normal year, falling on 24 days with 0.1 inch or more, the most in January (9.7 inches).
What is the rainiest month in Williamsport?
September, with 4.76 in of precipitation in a normal year; the driest is February with 2.31 in.
What plant hardiness zone is Williamsport in?
The USDA's 2023 map puts Williamsport in zone 6b in ZIP code 17702, the nearest ZIP area. By the same method at Williamsport's NOAA station, the coldest night of a typical year reaches −1°F (30 years, 1991-2020): zone 6b.
How late can frost come in Williamsport?
In half of years the last 32°F night comes after April 24; in one year in ten it comes after May 11. Waiting until May 11 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Williamsport in OctoberThis month day by day, its records and recent years
- Pennsylvania climateThe statewide normals and every place in the state
- Lewisburg, PA21 miles from this station, 50.4°F a year
- Laporte, PA25 miles from this station, 45.0°F a year
- Lock Haven, PA28 miles from this station, 50.3°F a year
- Sunbury, PA28 miles from this station, 50.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made