Longmont, CO Climate: Temperature & Rain by Month
Explore NOAA NCEI's 1991–2020 climate normals → and a clearly labeled PlainClimate comfort calculation
30-year climate normals (1991-2020) from Longmont's primary NOAA station, LONGMONT 2 ESE.
The climate verdict for Longmont
Dryness leads the climate profile for Longmont, Colorado, with 15.2 inches of precipitation a year. NOAA records an annual average of 50°F. At 52/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 24% of scores.
- 50°F
- yearly average temperature, NOAA normal
- 52/100
- comfort score, above 24% of station-mapped location scores
- 15.2"
- yearly precipitation total
- 151 days
- frost-free days per growing season
Longmont: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00055116 · Longmont, CO 50°F mean · 15.2" precip
TEMP-COOL · RANK-MID · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 50°F
- RANK-MID #2,744
- PHOTO-FINISH ≈ Nws Boston/nort…
- PRCP-DRY 15.2"
- SWING-MID 44°F
- COMF-LOW 52/100
- LOAD-HEAT 6,111 HDD
- STN-1 USC00055116
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Nws Boston/norton, MA (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every CO station list.
- Longmont (this station) 50°F
- Cold Genoa, CO 50°F
- Hot Fields, OR 50°F
- Near Nws Boston/nort…, MA 50°F
- Near La Grange, WY 50°F
Climate Living Index · Longmont
Longmont: 26/100 · grade F
Longmont publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Longmont, not an official NOAA rating. Rankings still use Comfort Score 52/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Annual temperature balance | 50.0°F · 17.5° from 67.5°F | 40/100 · D |
| Precipitation balance | 15.2 in · 19.8 from 35 in | 29/100 · F |
| Frost-free season | 151 days/year | 26/100 · F |
| Normal heat + freeze calendar | 210 calendar days | 9/100 · F |
Longmont · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Longmont's normals sit in a dry climate class: BSk
Precipitation is low relative to temperature but above true desert thresholds: cold semi-arid steppe (BSk). Class BSk is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically cold semi-arid steppe.
- Köppen code
- BSk
- Group
- Dry (arid or semi-arid)
- Warmest month
- 73.1°F
- Coldest month
- 29.4°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Longmont sits across the climate record
Three NOAA fields for Longmont's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 40th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Drier than 82%
- Longmont's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 52nd percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Longmont compares across U.S. station-mapped locations
Longmont's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
52 24th percentile score exceeds 24% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). This entry sits in this band.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Longmont's measured station temperature trend
MethodologyAcross 88 complete annual observations from 1895 to 2025, LONGMONT 2 ESE warmed at a fitted rate of 0.09°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Longmont primary station fitted change +0.09 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 45°F (7°C) | 14°F (-10°C) | 29°F (-1°C) | 0.6" | 30.6 | 0.0 |
| February | 47°F (8°C) | 17°F (-8°C) | 32°F (0°C) | 0.6" | 27.6 | 0.0 |
| March | 57°F (14°C) | 26°F (-3°C) | 42°F (5°C) | 1.2" | 26.6 | 0.0 |
| April | 63°F (17°C) | 32°F (0°C) | 48°F (9°C) | 2.0" | 15.8 | 0.0 |
| May | 73°F (23°C) | 41°F (5°C) | 57°F (14°C) | 2.0" | 2.8 | 1.2 |
| June | 84°F (29°C) | 51°F (10°C) | 67°F (20°C) | 1.8" | 0.1 | 9.2 |
| July | 91°F (33°C) | 55°F (13°C) | 73°F (23°C) | 1.7" | 0.0 | 17.1 |
| August | 88°F (31°C) | 54°F (12°C) | 71°F (22°C) | 1.9" | 0.0 | 15.4 |
| September | 80°F (27°C) | 46°F (8°C) | 63°F (17°C) | 1.3" | 1.6 | 5.8 |
| October | 66°F (19°C) | 33°F (0°C) | 50°F (10°C) | 1.0" | 15.2 | 0.1 |
| November | 54°F (12°C) | 24°F (-5°C) | 39°F (4°C) | 0.8" | 26.9 | 0.0 |
| December | 45°F (7°C) | 15°F (-10°C) | 30°F (-1°C) | 0.5" | 30.5 | 0.0 |
The year, day by day
Longmont works both ends of the calendar. Normal highs climb to 92°F by July 18 and hold at or above 90°F on 29 dates, then normal lows drop to freezing or below on 181 dates, bottoming at 13°F around December 23.
When the heat sits
Normal highs reach 90°F from July 5 through August 2, covering 29 dates. The broader mild season, normal highs of 70°F or more, runs May 9 to October 7.
This counts calendar dates whose 1991–2020 normal high reaches 90°F. It is a smaller number than the 90°F+ day counts in the monthly table above, which measure how often the threshold was actually crossed in a typical year. A date can average 88°F and still exceed 90°F in half of all years.
The freezing stretch
The normal low stays at or below 32°F into April 15, then returns to freezing around October 18, covering 181 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is May 26, when 33% of years recorded at least a hundredth of an inch. The driest is December 24 at 10%. Summed across the calendar, that is about 72 wet dates a year.
The widest day
July 12 carries the biggest normal gap between afternoon and dawn, 36°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Longmont.
Where Longmont Stands Nationally
Freezing is routine here by normals standards — the normal low reaches 32°F or colder on about 181 nights a year, more than most ranked stations.
A drier-than-most normal water year — around 15 inches, below what four out of five ranked stations collect.
Longmont earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
3.7 days with precipitation
4.5 days with precipitation
5.1 days with precipitation
7.5 days with precipitation
10.1 days with precipitation
8.3 days with precipitation
6.1 days with precipitation
7.4 days with precipitation
6.3 days with precipitation
5.4 days with precipitation
4.9 days with precipitation
3.0 days with precipitation
Longmont runs a summer-peaked wet season
35% of Longmont's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is April at 2.0", on a 43.7°F seasonal spread. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: April, May, August, taking 39% of the annual total between them.
- Driest month: December at 0.5".
- Winter share: 10% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
How Longmont's precipitation splits across the calendar
About 72 days a year record measurable precipitation here, carrying 15.2" between them, or roughly 0.21 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Frost Dates & Growing Season
First Fall Freeze
October 5
50% probability date
Last Spring Freeze
May 7
50% probability date
Growing Season
151 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
6,111
Higher = more heating needed
Cooling Degree Days
657
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside CO closest to Longmont on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (50°F here).
- Albia, IA 50°F · 0.0°F off
- Aledo, IL 50°F · 0.0°F off
- Centerburg, OH 50°F · 0.0°F off
- Circleville, UT 50°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (15.2" here), excluding temperature-peer places.
- White Signal, NM 15.2" · 0.0" off
- Conchas Dam, NM 15.2" · 0.0" off
- Sisters, OR 15.2" · 0.0" off
- Rapelje, MT 15.2" · 0.0" off
Data-derived climate profile
How Longmont's climate pattern fits together
heating led · dry · mid swing
Longmont's energy balance leans toward cold weather: 6,111 annual heating degree days against 657 for cooling. Its 43.7°F seasonal range still makes the monthly rows more useful than the annual average alone.
Longmont's frost-free season lasts about 151 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
July and January mark the typical warm and cold ends of the calendar in Longmont's middle-range seasonal profile. The measured spread is 43.7°F. The annual average is 50°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Longmont's cold-season load does not imply a wet climate. Annual precipitation is 15.2 inches, which places the station in PlainClimate's dry range. Snowfall is not added to the interpretation because its annual value is missing. The snowfall and rainfall fields should be read separately rather than inferred from temperature.
These labels group NOAA 1991-2020 normals from Longmont's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Longmont, not an official NOAA class or a year-ahead forecast.
Questions about Longmont's climate
How much rain does Longmont get? ▼
How many days above 90°F does Longmont get? ▼
How much energy does heating and cooling require in Longmont? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Longmont's primary station: LONGMONT 2 ESE (USC00055116). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 0845970). Match rule for Longmont: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Longmont comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.