Longmont in Fall
In fall (September, October and November), Longmont sees average daytime highs around 63°F and overnight lows near 38°F, with 4.3 in of precipitation over about 18 wet days across the season. It is the 2nd-warmest season and the 3rd-wettest season.
Over the season highs ease from about 81°F in early September to 45°F by late November. The sky is clear or mostly clear about 52% of the time across fall, and the air most often feels dry.
Fall is Longmont's 2nd-best season to visit on our travel score. For the whole year in context, see Longmont's year-round climate.
- Avg daytime high
- 63°F
- 2nd-warmest season
- Avg overnight low
- 38°F
- Precipitation
- 4.3 in
- 18 wet days
- Avg wind
- 4 mph
- Travel score
- 5.5
- 2nd-best season
- Months
- Sep · Oct · Nov
Temperature in Longmont in Fall
Over the season highs ease from about 81°F in early September to 45°F by late November.
A typical fall day in Longmont reaches about 63°F and drops to 38°F overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Longmont
Once humidity and wind are folded in, fall brings about 0 days that feel above 90°F and 42 that feel at or below 32°F.
The story in fall is cold — wind chill drags the overnight "feels like" below the raw low.
Longmont weather by month
How the three fall months (September, October and November) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 41° / 18° | 0.8 | 4.7 | 4.5 | 9.5 | 0.1 |
| Feb | 44° / 20° | 0.8 | 5.3 | 5 | 10.4 | 1.0 |
| Mar | 54° / 27° | 1.6 | 7.3 | 4.4 | 11.7 | 3.6 |
| Apr | 61° / 35° | 2.6 | 9.5 | 4 | 13 | 5.0 |
| May | 69° / 44° | 3.4 | 11.7 | 0.6 | 14.2 | 6.2 |
| Jun | 80° / 53° | 2.1 | 8.5 | 0 | 14.8 | 6.6 |
| Jul | 86° / 59° | 1.7 | 7.4 | 0 | 14.6 | 5.3 |
| Aug | 84° / 57° | 1.6 | 6.8 | 0 | 13.6 | 6.1 |
| Sep | 76° / 49° | 1.5 | 5.9 | 0.4 | 12.3 | 7.6 |
| Oct | 63° / 37° | 1.6 | 6.5 | 1.9 | 10.9 | 6.2 |
| Nov | 50° / 27° | 1.1 | 5.8 | 4.4 | 9.8 | 2.7 |
| Dec | 41° / 19° | 0.7 | 4.5 | 4.4 | 9.2 | 0.2 |
Cloud cover in Fall
The sky is clear or mostly clear about 52% of the time across fall.
Chance of precipitation in Fall
Longmont gets around 4.3 in of rain and snow over 18 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 4 mph across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 54 min in early September to 9 h 24 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 4.1 kWh/m².
Is fall a good time to visit Longmont?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit Longmont for sightseeing.
What to pack for Longmont in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Longmont sees daytime highs around 63°F and nights near 38°F. Pack a warm layer. Worth having: light clothes, a heavy coat and sun protection. About 18 days see rain.
UV index in Longmont in Fall
Clear-sky midday UV across fall averages around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Longmont peaks around July 13 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 4 | 7 | 6 | 7 | 11 | 11 | 10 | 7 | 5 | 3 | 2 |
| Level | Moderate | Moderate | High | High | Very high | Extreme | Extreme | Very high | Very high | High | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Moderate |
| Feb | 4 | Moderate |
| Mar | 7 | High |
| Apr | 6 | High |
| May | 7 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Very high |
| Sep | 7 | Very high |
| Oct | 5 | High |
| Nov | 3 | Moderate |
| Dec | 2 | Low |
Air quality in Longmont in Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall falls, not just the annual average.
Air quality in Longmont is worst in October — around 30 µg/m³ PM2.5 (moderate), about 3.1× the cleanest month (November, 10 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 12 | 12 | 14 | 11 | 11 | 12 | 14 | 19 | 17 | 30 | 10 | 11 |
| Level | Good | Moderate | Moderate | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 12 | Good |
| Feb | 12 | Moderate |
| Mar | 14 | Moderate |
| Apr | 11 | Good |
| May | 11 | Good |
| Jun | 12 | Good |
| Jul | 14 | Moderate |
| Aug | 19 | Moderate |
| Sep | 17 | Moderate |
| Oct | 30 | Moderate |
| Nov | 10 | Good |
| Dec | 11 | Good |
Where is Longmont?
Longmont sits at 40.2°N, 105.1°W, 4,984 ft above sea level, in United States. The nearest listed city is Erie, 8.7 mi away.
Topography around Longmont
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Longmont.
Within 2 miles, the terrain around Longmont has only modest variations in elevation — a maximum elevation change of 197 ft around an average of 4,993 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,765 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,721 ft.
The land around Longmont is covered by artificial surfaces (50%) and trees (22%) within 2 miles, grassland (54%) and cropland (25%) within 10 miles, and grassland (42%) and trees (31%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Longmont (40.1672°, -105.1019°, elevation 4,984 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.