May weather forecast
Rapid City, SD

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A scenic panorama of the Rapid City in South Dakota
A scenic panorama of the Rapid City in South Dakota

Weather in May

May manifests classic spring weather features in Rapid City. Residents begin to appreciate the warmer temperatures, extended daylight hours, and the beautiful blossoming flora associated with spring. Average rainfall during this time is 2.28" (58mm), with daylight spanning for an impressive 14.8 hours. The propensity for clear skies increases, increasing sunshine exposure for the city. Wind speed decreases slightly, marking an exceptionally calmer atmosphere.

Temperature

The arrival of May signals an increase in the average high-temperature, moving from a fresh 53.2°F (11.8°C) in April to a comfortable 63.1°F (17.3°C). In May, the recorded average low-temperature in Rapid City is a frosty 45.3°F (7.4°C).

Humidity

In Rapid City, the average relative humidity in May is 64%.

Rainfall

The month with the most rainfall is May, when the rain falls for 17.1 days and typically aggregates up to 2.28" (58mm) of precipitation.

Snowfall

Months with snowfall are January through May, September through December. May is the last month it regularly snows. During 1.3 snowfall days, in May, Rapid City aggregates 1.46" (37mm) of snow. In Rapid City, South Dakota, during the entire year, snow falls for 50.4 days and aggregates up to 24.41" (620mm) of snow.

Daylight

In Rapid City, the average length of the day in May is 14h and 47min.
On the first day of the month, sunrise is at 5:42 am and sunset at 7:56 pm. On the last day of May, in Rapid City, sunrise is at 5:12 am and sunset at 8:28 pm MDT.

Sunshine

The average sunshine in May in Rapid City, South Dakota, is 10.1h.

UV index

In May, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for the ordinary person.
Note: In May, a daily maximum UV index of 5 leads to the following instructions:
Adopt protective measures - Requirement to safeguard skin and eyes from harm exists. Minimize direct exposure to the Sun during midday when its radiation is at its peak. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays. Take precaution! The reflection from snow can almost double the UV radiation of the Sun.
Updated: Feb 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are May temperatures in Rapid City?

In May, the average high-temperature and low-temperature in Rapid City are 63.1°F (17.3°C) and 45.3°F (7.4°C) respectively.

What is the average humidity in May in Rapid City?

The average relative humidity in May in Rapid City, South Dakota, is 64%.

What is the wettest month in Rapid City?

May is the month with the most rainfall in Rapid City. Rain falls for 17.1 days and accumulates 2.28" (58mm) of precipitation.

How much does it rain in Rapid City in May?

In Rapid City, during May, the rain falls for 17.1 days and regularly aggregates up to 2.28" (58mm) of precipitation.

What is the last month it snows in Rapid City?

May is the last month it regularly snows in Rapid City. During 1.3 snowfall days, in May, Rapid City aggregates 1.46" (37mm) of snow.

What is the average length of the day in May in Rapid City?

In Rapid City, South Dakota, the average day length in May is 14h and 47min.

When are sunrise and sunset in May in Rapid City?

On the first day of May in Rapid City, sunrise is at 5:42 am and sunset at 7:56 pm. On the last day of the month, sunrise is at 5:12 am and sunset at 8:28 pm MDT.

How many hours of sunshine does Rapid City have in May?

The average sunshine duration in May is 10.1h.

What is the UV index reading in May in Rapid City?

In Rapid City, South Dakota, the average daily maximum UV index in May is 5. A UV Index estimate of 3 to 5 represents a medium hazard to health from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
Rapid City, SD

Average temperature in May - Rapid City, SD
  • Average high temperature in May: 63.1°F

The warmest month (with the highest average high temperature) is July (84.7°F).
The month with the lowest average high temperature is December (32.5°F).

  • Average low temperature in May: 45.3°F

The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is February (17.8°F).

Average pressure in May
Rapid City, SD

Average pressure in May - Rapid City, SD
  • Average pressure in May: 29.91"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.84"Hg).

Average wind speed in May
Rapid City, SD

Average wind speed in May - Rapid City, SD
  • Average wind speed in May: 9.8mph

The windiest month (with the highest average wind speed) is April (10.3mph).
The calmest month (with the lowest average wind speed) is August (8.2mph).

Average humidity in May
Rapid City, SD

Average humidity in May - Rapid City, SD
  • Average humidity in May: 64%

The month with the highest relative humidity is January (77%).
The months with the lowest relative humidity are August and September (50%).

Average rainfall in May
Rapid City, SD

Average rainfall in May - Rapid City, SD
  • Average rainfall in May: 2.28"

The wettest month (with the highest rainfall) is May (2.28").
The driest month (with the least rainfall) is January (0.43").

Average rainfall days in May
Rapid City, SD

Average rainfall days in May - Rapid City, SD
  • Average rainfall days in May: 17.1 days

The month with the highest number of rainy days is May (17.1 days).
The month with the least rainy days is December (4.8 days).

Average snowfall in May
Rapid City, SD

Average snowfall in May - Rapid City, SD
  • Average snowfall in May: 1.46"

The month with the highest snowfall is April (5.43").
The months with the least snowfall are June, July and August (0").

Average snowfall days in May
Rapid City, SD

Average snowfall days in May - Rapid City, SD
  • Average snowfall days in May: 1.3 days

The month with the highest number of snowfall days is February (10.5 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in May /
Average sunshine in May
Rapid City, SD

Average daylight in May / Average sunshine in May - Rapid City, SD
  • Average daylight in May: 14h and 5min

The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 8h and 54min).

  • Average sunshine in May: 10h and 1min

The month with the most sunshine is August (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 54min).

Average sunshine days in May
Rapid City, SD

Average sunshine days in May - Rapid City, SD
  • Average sunshine days in May: 11 days

The month with the most sunshine days is November (20.2 days).
The month with the least sunshine days is May (11 days).

Average UV index in May
Rapid City, SD

Average UV index in May - Rapid City, SD
  • Average UV index in May: 5

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in May
Rapid City, SD

Average cloud cover in May - Rapid City, SD
  • Average cloud cover in May: 34

The months with the most cloud cover are February and April (Cloud cover 38).
The month with the least cloud cover is August (Cloud cover 16).

Average visibility in May
Rapid City, SD

Average visibility in May - Rapid City, SD
  • Average visibility in May: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

Rapid City, South Dakota, USA

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