Longmont in Summer
In summer (June, July and August), Longmont sees average daytime highs around 83°F and overnight lows near 56°F, with 5.3 in of rain over about 23 wet days across the season. It is the warmest season of the year and the 2nd-wettest season.
Over the season highs climb from about 76°F in early June to 83°F by late August. The sky is clear or mostly clear about 38% of the time across summer, and the air most often feels dry.
Summer is Longmont's best season of the year to visit on our travel score. For the whole year in context, see Longmont's year-round climate.
- Avg daytime high
- 83°F
- warmest season of the year
- Avg overnight low
- 56°F
- Rainfall
- 5.3 in
- 23 wet days
- Avg wind
- 4 mph
- Travel score
- 6.0
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Longmont in Summer
Over the season highs climb from about 76°F in early June to 83°F by late August.
A typical summer day in Longmont reaches about 83°F and drops to 56°F overnight. The warmest of the three months is July, the coolest June.
How summer really feels in Longmont
Once humidity and wind are folded in, summer brings about 0 days that feel above 90°F and 0 that feel at or below 32°F.
summer sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Longmont weather by month
How the three summer months (June, July and August) 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 Summer
The sky is clear or mostly clear about 38% of the time across summer.
Chance of precipitation in Summer
Longmont gets around 5.3 in of rain over 23 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 4 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 36 min in early June to 13 hours by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 7.0 kWh/m².
Is summer a good time to visit Longmont?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit Longmont for sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Longmont in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Longmont sees daytime highs around 83°F and nights near 56°F. Pack light clothes and sun protection. Worth having: rain gear. About 23 days see rain.
UV index in Longmont in Summer
Clear-sky midday UV across summer averages around 10 (very high — sun protection essential). 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 Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer 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.