Alamosa, CO

Colorado · Records since 1906–2026

☀️ 77°F
Currently in Alamosa
As of 12:30 PM MDT

Records for September 11

🔥 Record High

89°F

September 11, 2021

+13° from 76° normal

❄ Record Low

28°F

September 11, 1986

-11° from 39° normal
🌞 Normal high: 76°F 🌑 Normal low: 39°F 1991–2020 normals

All-Time Records — Alamosa

🔥
96°F
Hottest Day Ever
Jul 5, 1989
❄
-50°F
Coldest Day Ever
Jan 28, 1948
🌧
1.77"
Wettest Day Ever
Sep 30, 1959
☃
15.8"
Most Snow in One Day
Dec 13, 1967

First & Last Dates — Alamosa

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)
124 days
Longest growing season
1958
10 days
Shortest growing season
2020
92 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 89°F September 11, 2021
2 83°F September 11, 1990
3 83°F September 11, 1956
4 82°F September 11, 1971
5 82°F September 11, 1959
6 82°F September 11, 1958
7 82°F September 11, 1945
8 81°F September 11, 2018
9 81°F September 11, 1998
10 81°F September 11, 1979

Top 5 Record Lows — September 11

# Temp Date
🥶 28°F September 11, 1986
2 28°F September 11, 1962
3 29°F September 11, 1987
4 29°F September 11, 1944
5 30°F September 11, 2020
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 1906–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Alamosa

threshold: 87°F (90th percentile of historical Jun–Aug highs)
4.7
Avg heat wave length
days (historical)
90°
Avg peak temp
during heat waves
0
Dangerous nights 2026
Overnights ≥ 70°F
5
Heat waves 2026
so far

Days ≥ 90°F Per Year

1934–2026
24
2026 so far
5
Avg/year 1970–2025
8
Avg/year (last 10 complete)
20
Most in a year (2003)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Alamosa

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 1, 2003 – Jul 26, 2003 26 93°F (Jul 13) 90°F 48°F
2 Jul 11, 2023 – Jul 31, 2023 21 95°F (Jul 17) 90°F 48°F
3 Jul 24, 2026 – Aug 12, 2026 20 93°F (Jul 26) 90°F 51°F
4 Aug 13, 2020 – Aug 26, 2020 14 92°F (Aug 19) 89°F 44°F
5 Jun 17, 2012 – Jun 27, 2012 11 93°F (Jun 24) 91°F 46°F
6 Jun 23, 1990 – Jul 2, 1990 10 93°F (Jun 29) 90°F 47°F
7 Jul 14, 2005 – Jul 23, 2005 10 92°F (Jul 17) 91°F 49°F
8 Jul 1, 1989 – Jul 9, 1989 9 96°F (Jul 5) 92°F 42°F
9 Jun 10, 2021 – Jun 18, 2021 9 94°F (Jun 16) 90°F 43°F
10 Jul 30, 2024 – Aug 7, 2024 9 92°F (Aug 5) 90°F 48°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

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

50
2026 total
above-normal nights
41.6
Avg / summer
1970–2020
67
Most in a summer
1957

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 (1906–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1906, annual totals have trended +0.16" per decade, about +1.9" 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 Alamosa is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

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

Precipitation, Year to Date

1.76"
2026 YTD
Normal: 5.45"
-3.69"
0.01"
September so far
September normal: 0.98"
-0.97"
0
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Alamosa is 3.69" behind the normal pace

Period Review — Jun 12 – Sep 10, 2026

Any window, evaluated against every other year on record — 91 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
66.5°F
Average temperature
1st-warmest of 95
+3.4°
vs. average
Normal: 63.1°F (1991–2020)

Average Temperature by Year — Jun 12 – Sep 10

1932–2026 · 2026 highlighted · trend +0.20° per decade (warming since 1932)

Precipitation by Year — Jun 12 – Sep 10

1932–2025 · 2026 highlighted · trend +0.02" per decade (wetter since 1932)

Warmest Jun 12 – Sep 10 on Record

# Year Avg Temp
1 2026 66.5°F
2 2021 65.4°F
3 2011 65.3°F
4 2023 65.0°F
5 2022 64.9°F
6 2007 64.8°F
7 2024 64.7°F
8 2013 64.6°F
9 2012 64.6°F
10 2018 64.0°F

Coolest Jun 12 – Sep 10 on Record

# Year Avg Temp
1 1941 60.6°F
2 1992 60.7°F
3 1976 60.9°F
4 2004 60.9°F
5 1950 61.1°F
6 1968 61.4°F
7 1993 61.4°F
8 1962 61.4°F
9 1943 61.5°F
10 1965 61.5°F
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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