Philadelphia, PA

Pennsylvania · Records since 1873–2026

☁️ 81°F Feels like 85°
Currently in Philadelphia
As of 2:15 PM EDT

Records for September 11

🔥 Record High

98°F

September 11, 1983

+17° from 81° normal

❄ Record Low

43°F

September 11, 1917

-20° from 63° normal
🌞 Normal high: 81°F 🌑 Normal low: 63°F 1991–2020 normals

All-Time Records — Philadelphia

🔥
106°F
Hottest Day Ever
Aug 7, 1918
❄
-11°F
Coldest Day Ever
Feb 9, 1934
🌧
8.02"
Wettest Day Ever
Jul 28, 2013
☃
27.6"
Most Snow in One Day
Jan 7, 1996

First & Last Dates — Philadelphia

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)
267 days
Longest growing season
1931
169 days
Shortest growing season
1966
226 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 98°F September 11, 1983
2 97°F September 11, 1931
3 96°F September 11, 1897
4 94°F September 11, 2013
5 94°F September 11, 1964
6 93°F September 11, 1989
7 92°F September 11, 1896
8 90°F September 11, 2019
9 90°F September 11, 1990
10 90°F September 11, 1915

Top 5 Record Lows — September 11

# Temp Date
🥶 43°F September 11, 1917
2 47°F September 11, 1976
3 47°F September 11, 1875
4 48°F September 11, 1969
5 48°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 1873–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Philadelphia

threshold: 92°F (90th percentile of historical Jun–Aug highs)
4.2
Avg heat wave length
days (historical)
97°
Avg peak temp
during heat waves
65
Dangerous nights 2026
Overnights ≥ 70°F
3
Heat waves 2026
so far

Days ≥ 90°F Per Year

1874–2026
41
2026 so far
22
Avg/year 1970–2025
35
Avg/year (last 10 complete)
55
Most in a year (2010)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Philadelphia

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 22, 1995 – Aug 5, 1995 15 98°F (Aug 2) 94°F 77°F
2 Aug 25, 1953 – Sep 4, 1953 11 101°F (Aug 31) 97°F 72°F
3 Jul 4, 1993 – Jul 14, 1993 11 101°F (Jul 10) 97°F 77°F
4 Jul 16, 1885 – Jul 26, 1885 11 97°F (Jul 18) 94°F 73°F
5 Aug 27, 1973 – Sep 5, 1973 10 99°F (Aug 28) 96°F 74°F
6 Jul 15, 1955 – Jul 23, 1955 9 100°F (Jul 22) 95°F 74°F
7 Aug 11, 2002 – Aug 19, 2002 9 99°F (Aug 13) 95°F 75°F
8 Aug 5, 1896 – Aug 13, 1896 9 97°F (Aug 11) 95°F 75°F
9 Jul 28, 2002 – Aug 4, 2002 8 99°F (Aug 1) 96°F 76°F
10 Jul 18, 2022 – Jul 25, 2022 8 99°F (Jul 24) 96°F 78°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

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

65
2026 total
above-normal nights
44.3
Avg / summer
1970–2020
67
Most in a summer
2022

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 (1871–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1871, annual totals have trended +0.30" per decade, about +4.6" 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 Philadelphia is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

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

Precipitation, Year to Date

32.01"
2026 YTD
Normal: 30.85"
+1.16"
2.28"
September so far
September normal: 4.40"
-2.12"
9
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Philadelphia is 1.16" 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)
77.9°F
Average temperature
12th-warmest of 153
+2.1°
vs. average
Normal: 75.8°F (1991–2020)
6.65"
Precipitation
26th-wettest of 155
+2.10"
vs. average
Normal: 4.55" · 146% of normal

Average Temperature by Year — Aug 11 – Sep 10

1874–2026 · 2026 highlighted · trend +0.23° per decade (warming since 1874)

Precipitation by Year — Aug 11 – Sep 10

1872–2026 · 2026 highlighted · trend +0.02" per decade (wetter since 1872)

Warmest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 2016 81.1°F
2 2015 79.5°F
3 1900 79.3°F
4 1959 78.8°F
5 2022 78.7°F
6 1993 78.6°F
7 1995 78.5°F
8 1980 78.2°F
9 2023 78.2°F
10 1973 78.0°F

Coolest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 1963 68.6°F
2 1940 69.0°F
3 1962 69.2°F
4 1946 69.9°F
5 1927 70.0°F
6 1883 70.4°F
7 1986 70.4°F
8 1903 70.6°F
9 1982 70.7°F
10 1909 70.9°F

Wettest Aug 11 – Sep 10 on Record

# Year Total
1 2011 21.22"
2 1873 12.57"
3 1911 11.80"
4 2018 10.23"
5 1935 9.88"
6 1901 9.52"
7 1955 8.98"
8 1933 8.87"
9 1999 8.82"
10 1926 8.61"

Driest Aug 11 – Sep 10 on Record

# Year Total
1 1944 0.21"
2 1874 0.24"
3 1980 0.34"
4 1995 0.42"
5 1964 0.42"
6 1883 0.67"
7 1976 0.69"
8 1895 0.70"
9 1943 0.72"
10 1886 0.72"
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.
← Back to all stations