Boulder, CO weather in May
In May, Boulder sees highs around 71°F and lows around 43°F: mild, with frequent rain. Rain or snow falls on about 13 days. Snowfall averages about 2.0 in.
- Normal high
- 71°F
- Normal low
- 43°F
- Wet days
- 13
- 3.2 in total
- Snowfall
- 2.0 in
- normal snowfall
How May changes from start to finish
| May 1 | May 31 | |
|---|---|---|
| Normal high | 66°F | 77°F |
| Normal low | 38°F | 47°F |
| Chance of a wet day | 38% | 40% |
| Sunrise / sunset | 6:00 am / 7:55 pm | 5:34 am / 8:22 pm |
| Daylight | 13.9 h | 14.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Mountain Time).
A typical May day
- 6 am48°Fdew point 38°F
- 9 am59°Fdew point 38°F
- Noon66°Fdew point 36°F
- 3 pm67°Fdew point 35°F
- 6 pm63°Fdew point 38°F
- 9 pm54°Fdew point 39°F
NOAA hourly normals (local standard time) from Denver Intl Airport (35 mi away); average wind 11 mph; clear or few clouds in 29% of daytime hours, mostly cloudy or overcast in 54%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F18 of 31
- Hot dayshigh 90°F or more1 of 31
- Muggy daysdaily mean dew point 65°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow13 of 31
- Notable rainat least 0.10 in7 of 31
- Freezing nightslow 32°F or below2 of 31
- Snow on the groundsnow depth 1 in or more0 of 31
Average days per May, counted from daily records for each year 1991-2020.
Rain and snow in May
Normal precipitation is 3.2 in; a dry May brings about 1.8 in and a wet one about 4.1 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more. Normal snowfall is 2.0 in, with about 1 day of an inch or more.
How May varies from year to year
- Warmest May, 1991-20201994: average high 77°F
- Coolest May1995: average high 62°F
- Wettest May1995: 9.6 in
- Driest May2006: 1.1 in
- Highest reading95°F (May 29, 2003)
- Lowest reading17°F (May 2, 2013)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
May compared with April and June
| April | May | June | |
|---|---|---|---|
| Normal high | 63°F | 71°F | 83°F |
| Normal low | 35°F | 43°F | 51°F |
| Wet days | 10 | 13 | 10 |
| Comfortable days | 14 | 18 | 10 |
| Daylight | 13.3 h | 14.4 h | 15.0 h |
Highs change by +8°F from April and +12°F into June.
Nearby alternatives in May
- Warmer: Pueblo, CO127 mi · high 77°F · 8 wet days
- Drier: Highlands Ranch, CO36 mi · high 68°F · 10 wet days
- Cooler: Estes Park, CO28 mi · high 60°F · 12 wet days
How Boulder ranks in May
- Normal high245th warmest of 378 cities; 5th of 17 in Colorado
- Wet days306th driest of 378
- Comfortable days31st most of 339
What to pack for Boulder in May
- Layers – afternoons near 71°F but nights near 43°F
- A rain jacket or umbrella – rain or snow on about 13 days
Frost in May
The last spring frost typically comes around May 6; in 1 year in 10 it comes after May 18. All frost dates for Boulder.
Heating and cooling
May has 265 heating degree days and 17 cooling degree days (base 65°F), 5% of the year's total heating and cooling demand.
Questions
How hot is Boulder in May?
The normal high is 71°F and the normal low is 43°F. From 1991 to 2020 the hottest May reading was 95°F (most recently on May 29, 2003).
Does it rain a lot in Boulder in May?
About 13 days in May have at least 0.01 in of precipitation, and the normal total is 3.2 in. The wettest May in 1991-2020 was in 1995 (9.6 in); the driest was in 2006 (1.1 in).
Does it snow in Boulder in May?
Yes. Normal snowfall in May is 2.0 in.
Is May a good time to visit Boulder?
May ranks 1st of 12 months on our comfort score for Boulder (76 out of 100). It has about 18 comfortable days and about 1 day at 90°F or hotter. The best month is May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth and frost dates: Boulder (USC00050848), 1.6 mi S of the city center, 5,484 ft (165 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour: Denver Intl Airport (USW00003017), 35 mi ESE of the city center, 5,414 ft (95 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Cloud cover: Aurora Buckley Fld ANGB (USW00023036), 35 mi SE of the city center, 5,663 ft (344 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Denver International Airport (725650-03017), 35 mi ESE of the city center, 5,404 ft (85 ft higher than the city). Hourly observations, 1991-2020.