San Francisco Airport, CA

California · Records since 1945–2026

☀️ 66°F
Currently in San Francisco Airport
As of 11:00 AM PDT

Records for September 11

🔥 Record High

98°F

September 11, 1979

+23° from 75° normal

❄ Record Low

49°F

September 11, 1951

-7° from 56° normal
🌞 Normal high: 75°F 🌑 Normal low: 56°F 1991–2020 normals

All-Time Records — San Francisco Airport

🔥
105°F
Hottest Day Ever
Jun 14, 2000
❄
24°F
Coldest Day Ever
Dec 9, 1972
🌧
5.59"
Wettest Day Ever
Jan 4, 1982
☃
1.5"
Most Snow in One Day
Jan 21, 1962

First & Last Dates — San Francisco Airport

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)

Top 10 Record Highs — September 11

# Temp Date
🏆 98°F September 11, 1979
2 96°F September 11, 1983
3 89°F September 11, 2003
4 89°F September 11, 1974
5 86°F September 11, 2017
6 86°F September 11, 1988
7 84°F September 11, 2010
8 83°F September 11, 1982
9 82°F September 11, 1998
10 81°F September 11, 2019

Top 5 Record Lows — September 11

# Temp Date
🥶 49°F September 11, 1951
2 50°F September 11, 1970
3 50°F September 11, 1962
4 50°F September 11, 1961
5 50°F September 11, 1948
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 1945–2026. Climate normals represent the 1991–2020 average.
4
days
🔥 Heat Wave in Progress
4 consecutive days at or above 79°F · since September 7
Heat wave in progress (3+ days ≥ 79°F)

Heat Wave Summary — San Francisco Airport

threshold: 79°F (90th percentile of historical Jun–Aug highs)
3.8
Avg heat wave length
days (historical)
90°
Avg peak temp
during heat waves
0
Dangerous nights 2026
Overnights ≥ 70°F
2
Heat waves 2026
so far

Days ≥ 90°F Per Year

1946–2026
3
2026 so far
4
Avg/year 1970–2025
5
Avg/year (last 10 complete)
12
Most in a year (1984)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — San Francisco Airport

# Dates Days Peak Avg High Avg Overnight Low
🏆 Oct 12, 2020 – Oct 21, 2020 10 94°F (Oct 16) 85°F 58°F
2 Jul 17, 2006 – Jul 25, 2006 9 97°F (Jul 22) 85°F 60°F
3 Sep 30, 2024 – Oct 7, 2024 8 98°F (Oct 6) 90°F 62°F
4 Jun 15, 1981 – Jun 22, 1981 8 92°F (Jun 15) 87°F 55°F
5 Aug 13, 2020 – Aug 19, 2020 7 99°F (Aug 14) 87°F 62°F
6 Sep 27, 2020 – Oct 3, 2020 7 96°F (Sep 28) 89°F 59°F
7 Oct 10, 1959 – Oct 16, 1959 7 87°F (Oct 13) 84°F 55°F
8 Aug 31, 2017 – Sep 5, 2017 6 104°F (Sep 1) 92°F 65°F
9 Jun 23, 1976 – Jun 28, 1976 6 97°F (Jun 24) 95°F 59°F
10 Sep 24, 2010 – Sep 29, 2010 6 96°F (Sep 27) 90°F 60°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

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

74
2026 total
above-normal nights
34.2
Avg / summer
1970–2020
82
Most in a summer
2015

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 (1945–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1945, annual totals have trended +0.17" per decade, about +1.3" 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 San Francisco Airport is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

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

Precipitation, Year to Date

10.78"
2026 YTD
Normal: 12.61"
-1.83"
0.01"
September so far
September normal: 0.07"
-0.06"
4
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · San Francisco Airport is 1.83" behind 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)
65.8°F
Average temperature
20th-warmest of 81
+0.7°
vs. average
Normal: 65.1°F (1991–2020)
0.04"
Precipitation
19th-wettest of 81
-0.01"
vs. average
Normal: 0.05" · 80% of normal

Average Temperature by Year — Aug 11 – Sep 10

1945–2026 · 2026 highlighted · trend +0.49° per decade (warming since 1945)

Precipitation by Year — Aug 11 – Sep 10

1945–2026 · 2026 highlighted

Warmest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 2015 68.9°F
2 2004 68.8°F
3 2017 68.6°F
4 2019 68.4°F
5 2020 68.3°F
6 2023 68.2°F
7 2022 68.1°F
8 1958 68.0°F
9 1997 67.5°F
10 1983 67.4°F

Coolest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 1955 60.6°F
2 1945 60.8°F
3 1949 61.2°F
4 1980 61.2°F
5 2012 61.4°F
6 1952 61.4°F
7 1973 61.4°F
8 1954 61.5°F
9 1948 61.6°F
10 1970 61.6°F

Wettest Aug 11 – Sep 10 on Record

# Year Total
1 1976 0.66"
2 1997 0.60"
3 1965 0.29"
4 1991 0.27"
5 1978 0.26"
6 1999 0.23"
7 1975 0.21"
8 1985 0.20"
9 1992 0.14"
10 1984 0.11"

Driest Aug 11 – Sep 10 on Record

# Year Total
1 2022 0.00"
2 2021 0.00"
3 2019 0.00"
4 2018 0.00"
5 2017 0.00"
6 2016 0.00"
7 2015 0.00"
8 2014 0.00"
9 2013 0.00"
10 2012 0.00"
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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