Williamsport, PA

Pennsylvania · Records since 1895–2026

☀️ 76°F
Currently in Williamsport
As of 2:00 PM EDT

Records for September 11

🔥 Record High

98°F

September 11, 1931

+21° from 77° normal

❄ Record Low

35°F

September 11, 1917

-21° from 56° normal
🌞 Normal high: 77°F 🌑 Normal low: 56°F 1991–2020 normals

All-Time Records — Williamsport

🔥
106°F
Hottest Day Ever
Jul 9, 1936
❄
-20°F
Coldest Day Ever
Jan 21, 1994
🌧
8.66"
Wettest Day Ever
Jun 22, 1972
☃
23.0"
Most Snow in One Day
Feb 22, 1902

First & Last Dates — Williamsport

How early and how late each seasonal turning point has ever arrived, across the full period of record

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Range ever recorded Normal date (1991–2020)
217 days
Longest growing season
1970
122 days
Shortest growing season
1963
173 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 98°F September 11, 1931
2 95°F September 11, 1900
3 93°F September 11, 1964
4 92°F September 11, 2019
5 92°F September 11, 1925
6 91°F September 11, 2013
7 91°F September 11, 1897
8 91°F September 11, 1895
9 90°F September 11, 1983
10 90°F September 11, 1896

Top 5 Record Lows — September 11

# Temp Date
🥶 35°F September 11, 1917
2 36°F September 11, 1995
3 38°F September 11, 1918
4 39°F September 11, 1932
5 40°F September 11, 1924
About this data — Records are sourced from the NOAA Threadex dataset via RCC ACIS, a quality-controlled record for long-term climate stations. Threadex adjusts for station relocations and observation-time changes, making records comparable across all years since 1895–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Williamsport

threshold: 91°F (90th percentile of historical Jun–Aug highs)
4.3
Avg heat wave length
days (historical)
96°
Avg peak temp
during heat waves
13
Dangerous nights 2026
Overnights ≥ 70°F
1
Heat waves 2026
so far

Days ≥ 90°F Per Year

1895–2026
14
2026 so far
16
Avg/year 1970–2025
22
Avg/year (last 10 complete)
42
Most in a year (1988)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Williamsport

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 4, 1988 – Jul 18, 1988 15 103°F (Jul 16) 97°F 64°F
2 Jul 14, 1955 – Jul 23, 1955 10 100°F (Jul 21) 95°F 64°F
3 Aug 27, 1953 – Sep 4, 1953 9 102°F (Sep 3) 98°F 64°F
4 Jun 18, 1923 – Jun 26, 1923 9 101°F (Jun 20) 97°F 65°F
5 Jul 17, 2011 – Jul 24, 2011 8 103°F (Jul 22) 95°F 70°F
6 Aug 2, 1930 – Aug 9, 1930 8 102°F (Aug 4) 98°F 63°F
7 Aug 10, 1944 – Aug 17, 1944 8 101°F (Aug 13) 96°F 65°F
8 Jul 16, 1991 – Jul 23, 1991 8 101°F (Jul 19) 97°F 65°F
9 Jul 7, 1993 – Jul 14, 1993 8 98°F (Jul 10) 95°F 68°F
10 Aug 11, 2002 – Aug 18, 2002 8 96°F (Aug 12) 93°F 66°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

Nights where the overnight low exceeded the 1991–2020 normal low

47
2026 total
above-normal nights
43.9
Avg / summer
1970–2020
75
Most in a summer
1901

Above-Normal Summer Nights Per Year

Average June–August Low by Decade

Overnight lows · complete decades only

Precipitation

Annual totals and trend across the full period of record · see this year's standing →

Monthly Precipitation — Last 24 Months

Blue = actual · dashed line = monthly normal

Annual Precipitation Per Year (1895–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1895, annual totals have trended +0.51" per decade, about +6.6" across the record.

Heavy Rain Days Per Year (≥ 1.0")

Compare year-to-year changes in days with heavy rainfall (≥ 1.0")

This Year — 2026

How Williamsport is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

121 of 253 days with data were above the 1991–2020 normal high for their date.

Precipitation, Year to Date

32.19"
2026 YTD
Normal: 30.04"
+2.15"
4.29"
September so far
September normal: 4.76"
-0.47"
8
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Williamsport is 2.15" ahead of the normal pace

Period Review — Aug 11 – Sep 10, 2026

Any window, evaluated against every other year on record — 31 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
71.1°F
Average temperature
38th-warmest of 132
+0.6°
vs. average
Normal: 70.6°F (1991–2020)
7.04"
Precipitation
14th-wettest of 127
+2.67"
vs. average
Normal: 4.37" · 161% of normal

Average Temperature by Year — Aug 11 – Sep 10

1895–2026 · 2026 highlighted · trend +0.09° per decade (warming since 1895)

Precipitation by Year — Aug 11 – Sep 10

1895–2026 · 2026 highlighted · trend +0.05" per decade (wetter since 1895)

Warmest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 1959 76.3°F
2 2016 75.7°F
3 1900 74.8°F
4 1947 74.6°F
5 2020 74.0°F
6 2018 73.7°F
7 2021 73.6°F
8 2015 73.5°F
9 1995 73.3°F
10 1980 73.2°F

Coolest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 1927 63.5°F
2 1982 64.6°F
3 1986 65.1°F
4 1946 65.3°F
5 1963 65.5°F
6 1940 65.6°F
7 1896 65.8°F
8 1994 66.2°F
9 1897 66.4°F
10 1902 66.5°F

Wettest Aug 11 – Sep 10 on Record

# Year Total
1 2011 12.61"
2 1999 10.90"
3 1933 10.57"
4 2006 10.25"
5 1926 9.03"
6 2018 8.82"
7 1988 8.49"
8 1911 7.70"
9 2023 7.30"
10 2021 7.21"

Driest Aug 11 – Sep 10 on Record

# Year Total
1 1995 0.21"
2 1925 0.60"
3 1972 0.69"
4 1982 0.75"
5 1931 0.79"
6 1929 0.98"
7 2020 1.03"
8 2013 1.03"
9 1908 1.04"
10 2024 1.12"
About this data. Pick any start and end date and this becomes the same kind of review as the Month and Fall tabs, just for exactly the window you asked for — the generalized version of the same engine, evaluated across every year on record. Average temperature is the mean of each day's (high + low) / 2; precipitation is the sum of daily totals. A year missing more than about a fifth of the window's days is excluded from the temperature ranking; any missing day excludes a year from the precipitation ranking, since an unreported day is unreported rain. Ranges that cross from December into January aren't supported yet. Normals are the 1991–2020 mean for the same window.
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