Rapid City, SD weather in May
Expect mild weather with frequent rain in Rapid City in May, with highs near 67°F and lows near 42°F. Rain or snow falls on about 13 days. Snowfall averages about 2.2 in.
- Normal high
- 67°F
- Normal low
- 42°F
- Wet days
- 13
- 3.5 in total
- Snowfall
- 2.2 in
- normal snowfall
How May changes from start to finish
| May 1 | May 31 | |
|---|---|---|
| Normal high | 61°F | 72°F |
| Normal low | 36°F | 47°F |
| Chance of a wet day | 38% | 44% |
| Sunrise / sunset | 5:44 am / 7:55 pm | 5:13 am / 8:28 pm |
| Daylight | 14.2 h | 15.3 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 am49°Fdew point 41°F
- 9 am58°Fdew point 42°F
- Noon62°Fdew point 42°F
- 3 pm64°Fdew point 42°F
- 6 pm61°Fdew point 43°F
- 9 pm53°Fdew point 42°F
NOAA hourly normals (local standard time) from Ellsworth AFB (8 mi away); average wind 11 mph; clear or few clouds in 38% of daytime hours, mostly cloudy or overcast in 50%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F15 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 below4 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 3.5 in; a dry May brings about 1.8 in and a wet one about 5.0 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more. Normal snowfall is 2.2 in, with about 1 day of an inch or more.
How May varies from year to year
- Warmest May, 1991-20201994: average high 74°F
- Coolest May2019: average high 58°F
- Wettest May1996: 8.2 in
- Driest May2016: 0.8 in
- Highest reading94°F (May 19, 2009)
- Lowest reading20°F (May 3, 2005)
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 | 57°F | 67°F | 78°F |
| Normal low | 31°F | 42°F | 52°F |
| Wet days | 11 | 13 | 13 |
| Comfortable days | 8 | 15 | 15 |
| Daylight | 13.5 h | 14.8 h | 15.4 h |
Highs change by +10°F from April and +11°F into June.
Nearby alternatives in May
- Cooler: Keystone, SD16 mi · high 60°F · 13 wet days
How Rapid City ranks in May
- Normal high322nd warmest of 378 cities; 3rd of 4 in South Dakota
- Wet days314th driest of 378
- Comfortable days104th most of 339
What to pack for Rapid City in May
- Layers – afternoons near 67°F but nights near 42°F
- A rain jacket or umbrella – rain or snow on about 13 days
Frost in May
The last spring frost typically comes around May 3; in 1 year in 10 it comes after May 17. All frost dates for Rapid City.
Heating and cooling
May has 349 heating degree days and 11 cooling degree days (base 65°F), 5% of the year's total heating and cooling demand.
Questions
How cold is Rapid City in May?
The normal high is 67°F and the normal low is 42°F. From 1991 to 2020 the coldest May reading was 20°F (May 3, 2005).
Does it rain a lot in Rapid City in May?
About 13 days in May have at least 0.01 in of precipitation, and the normal total is 3.5 in. The wettest May in 1991-2020 was in 1996 (8.2 in); the driest was in 2016 (0.8 in).
Does it snow in Rapid City in May?
Yes. Normal snowfall in May is 2.2 in.
Is May a good time to visit Rapid City?
May ranks 1st of 12 months on our comfort score for Rapid City (73 out of 100). It has about 15 comfortable days and about 1 day at 90°F or hotter. The best months are May and June.
Where the numbers come from
- Temperature and rain: Rapid City Rgnl Airport (USW00024090), 9.2 mi ESE of the city center, 3,160 ft (83 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Snowfall, snow depth and frost dates: Rapid City WFO (USC00396948), 1.1 mi ESE of the city center, 3,379 ft (136 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour and cloud cover: Ellsworth AFB (USW00024006), 8.1 mi NE of the city center, 3,215 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Rapid City Regional Airport (726620-24090), 9.1 mi ESE of the city center, 3,162 ft (81 ft lower than the city). Hourly observations, 1991-2020.