Flagstaff, AZ

Arizona · Records since 1898–2026

⛅ 79°F Feels like 75°
Currently in Flagstaff
As of 11:30 AM MST

Records for September 11

🔥 Record High

88°F

September 11, 1990

+12° from 76° normal

❄ Record Low

30°F

September 11, 2020

-14° from 44° normal
🌞 Normal high: 76°F 🌑 Normal low: 44°F 1991–2020 normals

All-Time Records — Flagstaff

🔥
97°F
Hottest Day Ever
Jul 5, 1973
❄
-30°F
Coldest Day Ever
Jan 22, 1937
🌧
3.93"
Wettest Day Ever
Feb 19, 1993
☃
35.9"
Most Snow in One Day
Feb 21, 2019

First & Last Dates — Flagstaff

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)
153 days
Longest growing season
2009
16 days
Shortest growing season
1912
111 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 88°F September 11, 1990
2 86°F September 11, 1945
3 85°F September 11, 1955
4 85°F September 11, 1944
5 84°F September 11, 1983
6 84°F September 11, 1948
7 84°F September 11, 1943
8 83°F September 11, 1993
9 83°F September 11, 1932
10 82°F September 11, 2015

Top 5 Record Lows — September 11

# Temp Date
🥶 30°F September 11, 2020
2 30°F September 11, 1986
3 31°F September 11, 1912
4 33°F September 11, 1950
5 33°F September 11, 1920
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 1898–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Flagstaff

threshold: 87°F (90th percentile of historical Jun–Aug highs)
4.6
Avg heat wave length
days (historical)
91°
Avg peak temp
during heat waves
0
Dangerous nights 2026
Overnights ≥ 70°F
3
Heat waves 2026
so far

Days ≥ 90°F Per Year

1900–2026
7
2026 so far
5
Avg/year 1970–2025
8
Avg/year (last 10 complete)
15
Most in a year (1974)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Flagstaff

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jun 11, 1974 – Jun 30, 1974 20 94°F (Jun 24) 91°F 51°F
2 Jul 12, 2023 – Jul 29, 2023 18 96°F (Jul 16) 91°F 56°F
3 Jul 4, 2003 – Jul 17, 2003 14 94°F (Jul 9) 90°F 52°F
4 Jun 20, 1990 – Jul 1, 1990 12 94°F (Jun 25) 92°F 52°F
5 Jul 3, 2024 – Jul 14, 2024 12 94°F (Jul 7) 91°F 52°F
6 Jun 16, 2017 – Jun 26, 2017 11 93°F (Jun 23) 90°F 51°F
7 Aug 2, 2025 – Aug 12, 2025 11 91°F (Aug 12) 88°F 51°F
8 Jul 12, 2005 – Jul 21, 2005 10 93°F (Jul 18) 90°F 54°F
9 Jun 30, 1989 – Jul 8, 1989 9 96°F (Jul 6) 91°F 48°F
10 Jul 1, 1985 – Jul 9, 1985 9 94°F (Jul 4) 90°F 53°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
39.7
Avg / summer
1970–2020
79
Most in a summer
2024

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 (1898–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1898, annual totals have trended +0.11" per decade, about +1.4" 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 Flagstaff is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

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

Precipitation, Year to Date

9.89"
2026 YTD
Normal: 14.48"
-4.59"
0.22"
September so far
September normal: 1.84"
-1.62"
1
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Flagstaff is 4.59" behind the normal pace

Period Review — Sep 3 – Sep 10, 2026

Any window, evaluated against every other year on record — 8 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
64.9°F
Average temperature
8th-warmest of 128
+3.6°
vs. average
Normal: 61.2°F (1991–2020)
0.01"
Precipitation
25th-driest of 128
-0.68"
vs. average
Normal: 0.69" · 1% of normal

Average Temperature by Year — Sep 3 – Sep 10

1899–2026 · 2026 highlighted · trend +0.26° per decade (warming since 1899)

Precipitation by Year — Sep 3 – Sep 10

1899–2026 · 2026 highlighted

Warmest Sep 3 – Sep 10 on Record

# Year Avg Temp
1 1945 68.4°F
2 2022 67.4°F
3 1977 67.2°F
4 1974 65.4°F
5 1948 65.3°F
6 1933 65.1°F
7 2024 65.1°F
8 2026 64.9°F
9 2019 64.8°F
10 1983 64.7°F

Coolest Sep 3 – Sep 10 on Record

# Year Avg Temp
1 1912 52.2°F
2 1985 53.1°F
3 1920 54.6°F
4 1961 54.8°F
5 1918 56.3°F
6 1929 56.7°F
7 1999 56.7°F
8 1915 56.8°F
9 1921 56.9°F
10 1901 57.1°F

Wettest Sep 3 – Sep 10 on Record

# Year Total
1 1970 3.67"
2 2002 3.26"
3 1924 2.75"
4 2013 2.65"
5 1949 2.29"
6 2003 2.28"
7 2011 2.22"
8 1998 1.85"
9 1909 1.65"
10 1939 1.65"

Driest Sep 3 – Sep 10 on Record

# Year Total
1 2023 0.00"
2 2020 0.00"
3 2001 0.00"
4 1999 0.00"
5 1993 0.00"
6 1992 0.00"
7 1988 0.00"
8 1979 0.00"
9 1973 0.00"
10 1971 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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