Boulder in Spring

In spring (March, April and May), Boulder sees average daytime highs around 55°F and overnight lows near 30°F, with 9.1 in of precipitation over about 35 wet days across the season. It is the 3rd-warmest season and the wettest season of the year.

Over the season highs climb from about 43°F in early March to 68°F by late May. The sky is clear or mostly clear about 28% of the time across spring, and the air most often feels dry.

Spring is Boulder's 3rd-best season to visit on our travel score. For the whole year in context, see Boulder's year-round climate.

Avg daytime high: 55°F; 3rd-warmest season
Avg overnight low: 30°F
Precipitation: 9.1 in; 35 wet days
Avg wind: 5 mph
Travel score: 3.2; 3rd-best season
Months: Mar · Apr · May

← Winter Boulder year-round climate Summer →

Spring Summer Fall Winter

Temperature in Boulder in Spring

Average highAverage lowShaded bands: 10–90% of days

Over the season highs climb from about 43°F in early March to 68°F by late May.

A typical spring day in Boulder reaches about 55°F and drops to 30°F overnight. The warmest of the three months is May, the coolest March.

How spring really feels in Boulder

Once humidity and wind are folded in, spring brings about 0 days that feel above 90°F and 71 that feel at or below 32°F.

Days feeling ≥ 90°F

heat index over the day's high

Days feeling ≤ 32°F

10 feel bitter (≤ 14°F)

The story in spring is cold — wind chill drags the overnight "feels like" below the raw low.

Boulder weather by month

How the three spring months (March, April and May) 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	37° / 14°	0.9	5.7	5.5	9.5	0.0
Feb	39° / 16°	1.0	6.7	7	10.4	0.0
Mar	48° / 22°	2.0	8.8	7.2	11.7	1.7
Apr	54° / 29°	3.1	11.1	7.9	13	3.1
May	63° / 38°	4.0	14.9	3.5	14.2	4.8
Jun	74° / 47°	3.0	14.3	0.3	14.8	6.2
Jul	80° / 53°	3.0	14.8	0	14.5	6.0
Aug	78° / 52°	2.8	14.9	0	13.6	6.2
Sep	71° / 44°	2.1	9.7	0.9	12.3	6.8
Oct	58° / 33°	1.9	7.4	3.9	10.9	4.9
Nov	46° / 22°	1.3	6.4	5.7	9.8	1.4
Dec	37° / 15°	0.9	5.3	5.4	9.2	0.0

Cloud cover in Spring

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% of the time across spring.

Chance of precipitation in Spring

Any precipitationSnow

Boulder gets around 9.1 in of rain and snow over 35 wet days across spring. The line is the day-by-day chance of measurable precipitation.

Humidity in Spring

DryComfortableHumidMuggyOppressiveMiserable

Most of spring feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

Wind in Spring

Winds average 5 mph across spring.

Sunrise & sunset in Spring

DaylightNight

Daylight runs from about 11 hours in early March to 14 h 36 min by late May. The lit band spans sunrise to sunset each day.

Solar energy in Spring

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day across spring, about 6.2 kWh/m².

Planning a trip in spring

Hazard calendar for Boulder

In seasonPeak

In spring, Boulder overlaps its rainy season season. The full year is below, with each hazard's peak months called out.

Boulder's rainy season runs March–October, when most of the year's rain falls.

Rainy season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is spring a good time to visit Boulder?

Our two travel scores rate spring for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.

3.2

Sightseeing

3rd-best month of the year

0.4

Beach & pool

3rd-best month of the year

spring is a weaker month for outdoor sightseeing in Boulder.

What to pack for Boulder in Spring

From spring's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In spring, Boulder sees daytime highs around 55°F and nights near 30°F. Pack a warm layer, rain gear and sun protection. Worth having: a heavy coat. About 35 days see rain.

a warm layerrain gearsun protectiona heavy coat

UV index in Boulder in Spring

LowModerateHighVery highExtreme

Clear-sky midday UV across spring averages around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Boulder 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 Boulder in Spring

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where spring falls, not just the annual average.

Air quality in Boulder is worst in August — around 21 µg/m³ PM2.5 (moderate), about 1.6× the cleanest month (May, 13 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)	17	15	16	13	13	14	14	21	13	15	15	16
Level	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	PM2.5 (µg/m³)	Level
Jan	17	Moderate
Feb	15	Moderate
Mar	16	Moderate
Apr	13	Moderate
May	13	Moderate
Jun	14	Moderate
Jul	14	Moderate
Aug	21	Moderate
Sep	13	Moderate
Oct	15	Moderate
Nov	15	Moderate
Dec	16	Moderate

Location & terrain

Where is Boulder?

Boulder sits at 40.0°N, 105.3°W, 5,328 ft above sea level, in United States. The nearest listed city is Louisville, 8.1 mi away.

Topography around Boulder

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Boulder.

Within 2 miles, the terrain around Boulder has significant variations in elevation — a maximum elevation change of 1,703 ft around an average of 5,495 ft above sea level; within 10 miles, very significant variations in elevation — a maximum elevation change of 4,147 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,623 ft.

The land around Boulder is covered by trees (45%) and artificial surfaces (39%) within 2 miles, grassland (44%) and trees (41%) within 10 miles, and trees (41%) and grassland (34%) within 50 miles.

2 miles

1,703 ft

trees 45%

10 miles

4,147 ft

grassland 44%

50 miles

9,623 ft

trees 41%

treesgrasslandcroplandartificial surfacesbare terrainwatermoss and lichen

← Winter Boulder year-round climate Summer →

Spring weather nearby: Louisville 8.1 mi · Lafayette 9.9 mi · Broomfield 12 mi · Erie 12 mi · Longmont 14 mi · Westminster 17 mi · Northglenn 17 mi · Arvada 17 mi

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 Boulder (40.015°, -105.2706°, elevation 5,328 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.