Boulder Colorado Weather Resources: Forecasts and Live Links

calendar Aug 19, 2025 / · 8 min read · Boulder weather Colorado forecasts NOAA NCAR climate safety  ·
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Weather In Boulder or Boulder Weather

Boulder's official temperature record comes from a station beside the NIST building on the western edge of town, which has logged the city's highs and lows there since 1990. Earlier observations were made at several addresses in the western part of the city, near the University of Colorado campus from 1912 to 1936, on the campus from 1936 to 1947, and then at the Central Fire Station until 1989. Records are essentially complete from 1897, with a single missing year around 1989-1990. That long, mostly continuous record is what makes the links below worth bookmarking: each one points to either a live observation or the data that tells you what a normal day looks like.

The numbers give a sense of scale. The daily normals put a mid-January afternoon at 45°F with a low of 23°F, a mid-April day at 62°F and 36°F, a mid-July day at 85°F and 58°F, and a mid-October day at 66°F and 40°F. The same table lists a lowest daily minimum of -33°F on January 17, 1930, and a highest daily maximum of 104°F, recorded on June 23, 1954, July 11, 1954 and August 3, 2026. Snow records start in 1948; temperature records start in 1897.

Boulder & Colorado Weather Resources

For a statewide view, the Colorado weather page on this site covers radar and mountain conditions, and the Boulder versus Denver comparison explains why the two forecasts differ by a few degrees.

Frost, Snow and Seasons in the Record

Boulder's frost dates are the clearest example of how much a single year can mislead. The first fall frost, defined as a minimum of 32°F or lower, arrives on average October 6, with a median of the same day and a middle half of years falling between September 27 and October 15. The earliest in the 1948-onward record was September 8, 2020, and the latest on the full record was November 2, 1902. In spring, the last frost averages May 5 and the median is May 3, with a range from April 3 in 2012 to early June in 1951. The spread is wide: the standard deviation is 11.6 days. The freeze dates and garden planning post works through what those numbers mean for a Boulder yard.

Snow follows the same pattern of wide spread. The first measurable snow of the season has averaged October 17 since 1948, ranging from September 12 in 1974 to November 17 in 2016. The last measurable snow averages April 27 in the 1949-2014 statistics, with the earliest finish on March 22, 1992 and the latest on June 7, 1993. Between those dates, the 1991-2020 monthly snowfall averages at the NIST site run 11.76 inches in January, 14.78 in February, 14.59 in March and 13.59 in April, for a yearly mean of 89.71 inches, so late winter outweighs midwinter. The month-by-month normals lay that out in order.

Summer heat varies just as much from year to year. The count of days at or above 90°F at the Boulder station reached 59 in 2012, with 17 of them in June, 20 in July and 18 in August, and fell to only 5 in 1992. A forecast of a hot week says little about the season, which is why the daily normals and records are a better yardstick than any single summer.

Wind: The Part of Boulder Weather That Is Not Like Denver

Boulder has some of the highest peak winds of any city in the United States, and its wind history shows why. A gust of 147 mph was recorded at NCAR on January 23, 1971, a single reading at that site only. On January 7-8, 1969 NCAR logged a 130 mph gust, and on December 30, 2021 gusts reached 108 mph in south-southwest Boulder, 110 mph at Rocky Flats and 115 mph in Arvada. More recently, a localized windstorm on November 14, 2021 brought 81 mph at the NCAR Mesa Lab, two miles southwest of Boulder.

Those storms are the downslope windstorms the city knows as Chinook winds, and the same log lists the fires they have fed: April 6-7, 1969, January 18, 2006, January 7, 2009, February 9-10, 2017 and December 30, 2021. The last of those was the Marshall Fire, which destroyed 1,094 houses plus commercial structures; the weather setup for that day has its own page. The practical lesson is that a Boulder forecast with a high wind watch is a different event from a breezy afternoon, and the NWS office's fire weather and hazard pages are the first place to read it.

Thunderstorms and Hail

Thunderstorm days are a summer feature. The monthly thunderstorm table gives a 1991-2020 average of 7.0 days in May, 11.2 in June, 12.0 in July, 11.5 in August and 5.2 in September, against 0.0 in January and February. The most active year in the table is 1991, with 72 thunderstorm days. The daily rhythm behind those counts is covered in afternoon storms on the Front Range and in the hail season guide.

Severe storms occasionally include tornadoes. The Boulder-area tornado listing shows an F1 tornado near Baseline Road in east Boulder on June 6, 1997 and another F1 at Pinecliff, west of the city, on June 16, 1996. Lightning is the more common hazard: lightning kills about 20 people in the United States each year.

Boulder, CO Webcams for Current Weather Conditions

A camera is the quickest way to check whether the snow line has dropped or the Flatirons are under cloud.

  • Boulder Cam
    The Boulder Cam is mounted on the West End Plaza building at 1035 Pearl St. and pans from the Flatirons and Chautauqua Park to Flagstaff Mountain and Mt. Sanitas, then across West Pearl Street and east toward the CU campus.

  • NOAA PSL Boulder-area webcam list
    The lab keeps a list of area cameras, including the Eldora Ski Area, a Flatirons view, Boulder Reservoir and Highway 36 views, and notes that cameras come and go, so some links will lapse.

  • NOAA and NCAR observation stations
    The regional observations page links current readings from the NCAR Foothills Lab in northeast Boulder, the NCAR Mesa Lab, the NOAA Skaggs Building, the CU East Campus and the National Laboratory of the Rockies Flatirons Campus.

  • Boulder County trailhead cameras
    The county's live trailhead cameras show parking lots at Walker Ranch, the Corral Trailhead at Heil Valley Ranch, Coalton Trailhead in Superior, Pella Crossing, Carolyn Holmberg Preserve and Ron Stewart Preserve at Rabbit Mountain. Images refresh about every ten minutes between 5 a.m. and 10 p.m., and the solar-powered cameras may not work during cloudy weather.

References

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