January Weather in Boulder, United States

Last updated: February 24, 2025

January weather in Boulder, United States presents a fascinating mix of conditions, where the maximum temperature reaches a mild 15°C (59°F), while the average temperature sits at a chilly -3°C (26°F), dipping to a brisk minimum of -24°C (-12°F). This month experiences moderate precipitation, accumulating about 25 mm (1.0 in) over 5 days, complemented by a relatively high humidity level of 88%. Whether you’re embracing the wintry landscape or bracing for the cold, Boulder’s January weather offers a unique charm that captivates both residents and visitors alike.

January Temperature in Boulder

January in Boulder, United States, showcases a stark winter climate, with temperatures ranging from a chilling minimum of -24°C (-12°F) to a relative peak of 15°C (59°F). The average temperature hovers around -3°C (26°F), hinting at the cold grip that often dominates this month. This trend reflects the broader seasonal pattern where January generally presents some of the year’s coldest conditions, just slightly less severe than February's even lower averages. As winter progresses, the temperatures gradually begin to rise, leading into the milder months ahead, marked by notable shifts in both minimum and maximum temperatures as spring approaches. The transition from January’s frigid days to February’s even chillier nights certainly prepares Boulder residents for the eventual thaw, setting the stage for the warmth that follows in the spring months.

January Weather in Boulder: Daily Temperature Highs, Lows, and Averages

The chart illustrates January temperature patterns in Boulder, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec262535425063686661443629
Data source: Temperature data for Boulder generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

January Precipitation in Boulder

In January, Boulder experiences relatively low precipitation, with an average of just 25 mm (1.0 in) over approximately 5 days of rain. This sets the tone for a cold and crisp winter month, where the snowfall can be inconsistent but often light. As the year progresses, February sees a slight increase in both rainfall and rainy days, hinting at the transition towards spring. By March, the city begins to witness a noticeable uptick in moisture, with totals climbing to 62 mm (2.5 in) over 11 days, foreshadowing the vibrant blooms of May, which experiences the most precipitation at 134 mm (5.3 in) across 16 days. Overall, the pattern reveals a gradual increase in rainfall from January through to late spring, reflecting Boulder’s dynamic seasonal shifts and setting the stage for lush greenery in the warmer months.

January Precipitation Trends in Boulder

The chart displays monthly precipitation patterns in Boulder, with values for each month alongside January's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how January's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec2536636813474716842483020
Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

January Humidity in Boulder

In January, Boulder experiences its highest humidity of the year at 88%, creating a chilly and damp atmosphere that sets the tone for winter. As the month transitions into February, humidity slightly decreases to 87%, signaling the slow approach of spring. This downward trend continues through the following months, with March at 81% and April dropping to 76%, as the air begins to dry out. By May, humidity reaches a much more comfortable 66%, paving the way for the warmer summer months. However, towards the peak of summer in July, humidity levels plummet to 52%, providing a refreshingly dry respite. As the year progresses into the fall, humidity begins to rise again, peaking in December at 89%, reminiscent of the winter's embrace. This cyclical pattern showcases Boulder's unique climate, where high humidity levels in winter contrast sharply with the aridness of summer, creating a dynamic seasonal experience.

January Average Humidity in Boulder

This chart illustrates the average monthly humidity levels in Boulder, with January's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how January's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%81%76%67%58%52%56%65%76%82%89%
Data source: Humidity data for January generated using information from the Copernicus Climate Change Service.

January UV Index in Boulder

In Boulder, January marks the beginning of a gradual rise in the UV Index, with a moderate rating of 4, indicating that the potential for skin damage is present with prolonged exposure—approximately 30 minutes without protection. As the months progress into February, the UV Index escalates to 6, representing a high exposure risk, which tightens the burn time to 25 minutes. By March, this trend continues sharply upward, reaching a very high level of 9 and reducing the burn time significantly to just 15 minutes. The peak intensity occurs in the summer months, with the UV Index soaring to an extreme 12 in June and July, necessitating vigilance to avoid sunburn within a mere 10 minutes of exposure. As the year winds down, the UV Index reflects a cooling off, dipping back to moderate levels of 4 in both December and January. This annual cycle underscores the importance of sun safety practices throughout the year. For more detailed information, check out Boulder UV Index.

Maximum UV Index Levels in Boulder for January

The chart shows the monthly maximum UV Index (UVI) for Boulder in January, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec469111112121110754
Data source: Boulder January UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

January Sunshine in Boulder

January brings a modest 185 hours of sunshine to Boulder, setting the stage for a gradual increase in daylight as winter gives way to spring. By February, the sun's presence grows to 237 hours, signaling the end of the cold season. As the months progress, the sun's embrace becomes more generous, with March and April boasting 288 hours and 304 hours respectively, inviting more outdoor activities. The trend continues through May and June, peaking at 374 hours in June, where long, sunny days invite residents to fully enjoy the beauty of the Rockies. July maintains this warmth slightly higher at 378 hours, before sunlight begins to wane in August. As summer transitions to fall, the hours decrease steadily, culminating in 238 hours in December. This clear progression not only highlights Boulder’s seasonal charm but also showcases how each month brings its own unique sunlight experience, encouraging exploration and appreciation of the outdoors.

Monthly Sunshine Duration in Boulder: January Highlighted

The January sunshine duration represents the total number of hours Boulder experiences direct sunlight during the month of January, excluding cloudy or obstructed periods. This chart compares the sunshine duration of January with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec185h237h288h304h330h374h378h351h309h274h249h238h
Data source: Boulder January Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Boulder During January

In Boulder, January ushers in a moderate likelihood of sunny weather, boasting a 56% chance of sunshine. This trend marks the start of a gradual increase in sunshine that peaks in late summer. As the months progress, February follows closely behind at 52%, while March and April hover around the 50% mark, suggesting a consistent yet slightly diminishing chance of clear skies. By the time we reach the sun-drenched days of August, the probability rises to an impressive 65% before tapering off again into autumn. This seasonal pattern highlights Boulder’s unique climate, where winter sun is a welcomed precursor to the vibrant warmth of summer.

Percentage of Sunny Days in January in Boulder

The chart illustrates the percentage of sunny days in Boulder throughout the year, with January highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Boulder experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec56%52%50%51%41%55%59%65%69%63%63%68%
Data source: Boulder January chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Boulder in January

In Boulder, Colorado, January brings about 9 hours of daylight, setting the stage for a gradual increase as winter gives way to spring. As February rolls in, daylight extends to 10 hours, hinting at the longer, sunnier days ahead. The trend continues into March with 11 hours, and by April, Boulder's skies bask in a generous 13 hours of light. This peak of daylight reaches its zenith in the summer months, with May, June, and July each showcasing a consistent 14 hours of glorious sunlight. As the year transitions back toward winter, daylight begins to wane, descending from 13 hours in August to 11 in October, ultimately returning to 9 hours by December. This rhythmic ebb and flow of daylight not only marks the changing seasons but also invigorates Boulder's vibrant outdoor lifestyle throughout the year.

Average Daylight Hours in Boulder for January

The chart illustrates the variation in daylight duration in Boulder throughout the year, with January highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 40m10h 41m11h 58m13h 18m14h 24m14h 57m14h 39m13h 39m12h 23m11h 5m9h 56m9h 21m
Data source: Boulder daylight hours, calculated by summing the hours between sunrise and sunset for each day.

January Winds in Boulder

In Boulder, United States, the January wind carries a gentle whisper, with an average speed of 2.6 m/s (6 mph), slightly lower than the following month but comfortably consistent for winter. As winter transitions to spring, February sees a minor uptick in wind speed, nudging up to 2.8 m/s, while March settles back down to 2.5 m/s. This trend of subtle variations continues into the spring, where April to July exhibits a steady wind pattern around 2.1 to 2.4 m/s. Interestingly, as summer gives way to autumn, a pronounced shift occurs, with November seeing a noteworthy increase to 2.9 m/s and December escalating to 3.0 m/s—the strongest winds of the year. Overall, January's winds set the stage for a year where breezes are mild yet unmistakably present, embodying the charm of Boulder’s winter landscape.

Average January Wind Speed in Boulder

The chart displays monthly wind speed patterns in Boulder, with values for each month shown alongside January's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how January's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec2.6 m/s2.82.52.42.12.32.12.22.22.42.93.0
Data source: Boulder January wind data, generated using information from the Copernicus Climate Change Service.

How January Weather in Boulder Compares to Other Months

The weather in Boulder changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of January's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Boulder and find detailed weather information for every month.

In January, the weather features a broader temperature range with lows hitting -24°C (-12°F) and a maximum of 15°C (59°F), while February brings slightly colder minimum temperatures of -26°C (-14°F) but a higher maximum of 20°C (69°F). Precipitation increases in February, with 36 mm (1.4 in) falling over 9 days compared to January's 25 mm (1.0 in) over 5 days. Both months maintain high humidity, with January at 88% and February slightly lower at 87%. For more details on the February climate, check out this link: Boulder weather in February.

January and March exhibit notable differences in weather patterns. In January, the temperatures are generally colder, with an average of -3°C (26°F), while March sees a slight increase, averaging around 2°C (35°F). Both months experience frigid nights, but March can reach a maximum of 23°C (73°F), much warmer compared to January's peak of 15°C (59°F). Additionally, March tends to be wetter, receiving 62 mm (2.5 in) of precipitation over 11 days, compared to January's 25 mm (1.0 in) over just 5 days. The humidity remains relatively high in January at 88%, slightly lower in March at 81%. For more specific details, you can check Boulder weather in March.

January weather is characterized by frigid temperatures, with a minimum of -24°C (-12°F) and an average of -3°C (26°F), while the maximum can reach only 15°C (59°F). In contrast, April experiences a broader temperature range, with a minimum of -17°C (2°F), an average of 5°C (42°F), and a maximum of 24°C (75°F). Precipitation also sees a notable increase in April, totaling 68 mm (2.7 in) over 12 days compared to January’s 25 mm (1.0 in) over just 5 days. Furthermore, January maintains a higher humidity level at 88%, while April's humidity settles at a more comfortable 76%. For a detailed overview of Boulder’s weather in April, check out Boulder weather in April.

In comparing the weather between January and May, January presents a frigid climate with temperatures ranging from a minimum of -24°C (-12°F) to a maximum of 15°C (59°F), averaging around -3°C (26°F). The month sees relatively low precipitation at 25 mm (1.0 in) over just 5 days, but the high humidity of 88% can make the cold feel even more biting. In contrast, May ushers in a significant shift with temperatures varying from a minimum of -9°C (17°F) to a pleasant maximum of 27°C (81°F), averaging 10°C (50°F). However, May also experiences heightened precipitation at 134 mm (5.3 in) across 16 days, accompanied by a drop in humidity to 66%. For a deeper understanding of what to expect during this month, you can check Boulder weather in May.

In January, temperatures can plunge to a frigid minimum of -24°C (-12°F), with an average temperature around -3°C (26°F) and a maximum of 15°C (59°F). This month experiences high humidity levels at 88% and relatively low precipitation, with only about 25 mm (1.0 in) falling over 5 days. In stark contrast, June brings a much milder climate, with temperatures ranging from a minimum of 3°C (37°F) to an average of 17°C (63°F), and highs that can reach up to 34°C (93°F). The month sees more rainfall, totaling approximately 74 mm (2.9 in) over 14 days, alongside a significantly lower humidity of 58%. For those interested in specific June conditions, check out Boulder weather in June.

January and July present strikingly different weather conditions. In January, temperatures can plummet to a minimum of -24°C (-12°F), with an average of -3°C (26°F) and a maximum of 15°C (59°F). The month sees relatively low precipitation at 25 mm (1.0 in) over just 5 days, accompanied by high humidity levels of 88%. In stark contrast, July offers a much milder climate, with minimum temperatures around 7°C (45°F), an average of 20°C (68°F), and highs reaching up to 34°C (93°F). Rainfall is more frequent in July, totaling 71 mm (2.8 in) across 16 days, and the humidity drops significantly to 52%. For more detailed insights, check Boulder weather in July.

In January, the weather is characterized by biting cold, with temperatures ranging from a chilling -24°C (-12°F) to a more moderate max of 15°C (59°F) and an average of -3°C (26°F). The month sees low precipitation levels at 25 mm (1.0 in) over about 5 days, but high humidity at 88%, creating a damp and frigid atmosphere. In contrast, August brings much warmer conditions, with temperatures ranging from a minimum of 7°C (45°F) to a sweltering maximum of 33°C (91°F), averaging around 19°C (67°F). This summer month experiences higher rainfall at 67 mm (2.7 in) over 13 days, and the humidity drops to a more comfortable 56%. Overall, the winter chill of January starkly contrasts with the warmth and occasional rain of August. For more detailed information, you can visit Boulder weather in August.

In January, the weather is characterized by frigid temperatures, with a minimum of -24°C (-12°F) and an average of -3°C (26°F), while the maximum reaches only 15°C (59°F). The month sees relatively low precipitation at 25 mm (1.0 in) over about 5 days, combined with high humidity levels at 88%. In contrast, September offers a much milder climate, with temperatures ranging from a minimum of -4°C (25°F) to an average of 16°C (61°F) and a high of 33°C (92°F). This month experiences increased precipitation, totaling 42 mm (1.6 in) over 8 days, and lower humidity at 65%. For more details, check out Boulder weather in September.

When comparing January and October, it's evident that October brings milder weather with a significant temperature rise. January's temperatures range from a chilling minimum of -24°C (-12°F) to a max of 15°C (59°F), creating an overall average of -3°C (26°F). In contrast, October features a much warmer average of 7°C (45°F), with temperatures reaching up to 26°C (79°F). Additionally, October experiences more precipitation, totaling 48 mm over about 7 days, compared to January's 25 mm over 5 days, though the humidity is slightly lower at 76%. For more detailed information, check out Boulder weather in October.

January and November exhibit notable differences in weather patterns. January is generally colder, with average temperatures hovering around -3°C (26°F) and reaching a minimum of -24°C (-12°F), while November is milder with an average of 2°C (36°F) and a minimum of -16°C (3°F). Both months experience a relatively similar level of precipitation, with January receiving 25 mm (1.0 in) over five days, compared to November's 30 mm (1.2 in) over six days. Additionally, January tends to be slightly more humid at 88%, while November has a humidity level of 82%. For a closer look at the weather specifics in November, refer to Boulder weather in November.

In comparing the weather of January and December, we see some notable differences and similarities. January experiences slightly colder temperatures with a minimum of -24°C (-12°F) and an average temperature of -3°C (26°F), while December is milder, with a minimum of -19°C (-1°F) and an average of -2°C (29°F). Precipitation levels are similar, with January receiving 25 mm (1.0 in) over about 5 days and December having 19 mm (0.8 in) over 4 days. Humidity remains high in both months, at 88% in January and 89% in December. For more specific details on December's climate, you can check Boulder weather in December.

Compare Boulder's Climate with Cities Worldwide

Conclusion: What to Expect From January Weather in Boulder

January in Boulder is a month characterized by significant fluctuations in temperature, with chilly averages and occasional warmer peaks, creating a stark contrast to the milder months of spring and fall. While the presence of precipitation, though modest, marks about five days, the high humidity level of 88% can amplify the cold, giving the air a biting chill. This month often feels colder than others, compelling residents and visitors to bundle up and embrace the winter wonderland. For a deeper insight into Boulder’s weather patterns throughout the year, check out Boulder Climate.