The most pleasant months of the year for Irwin are September, June and August. In Irwin, there are 2 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for Irwin with an average high temperature of 87.3°, which ranks it as warmer than most places in South Dakota. March is the snowiest month in Irwin with 8.5 inches of snow, and 7 months of the year have significant snowfall. But there some days when the humidity becomes unpleasant, especially in July and August.
Weather Highlights
Summer High: the July high is around 87 degrees
Winter Low: the January low is 12
Rain: averages 24 inches of rain a year
Snow: averages 44 inches of snow a year
BESTPLACES COMFORT INDEX
The annual BestPlaces Comfort Index for the Irwin area is 7.1 (10=best), which means it is more comfortable than most places in South Dakota.
7.1 / 10
A higher score indicates a more comfortable year-round climate. The US average for the comfort index is 7. Our index is based on the total number of days annually within the comfort range of 70-80 degrees, and we also applied a penalty for days of excessive humidity.
Average Monthly High and Low (°F)
| High | Low |
| January | 34° | 12° |
| February | 37° | 15° |
| March | 47° | 24° |
| April | 59° | 35° |
| May | 70° | 46° |
| June | 80° | 56° |
| July | 87° | 62° |
| August | 86° | 60° |
| September | 77° | 50° |
| October | 63° | 37° |
| November | 46° | 24° |
| December | 34° | 13° |
Hot, Freezing, Rainy, Snowy Days: Irwin
| Hot
Days | Freezing
Days | Rainy
Days | Snowy
Days |
| January | 0 | 30 | 3 | 3 |
| February | 0 | 27 | 3 | 3 |
| March | 0 | 24 | 5 | 2 |
| April | 0 | 11 | 8 | 1 |
| May | 1 | 1 | 9 | 0 |
| June | 3 | 0 | 10 | 0 |
| July | 11 | 0 | 8 | 0 |
| August | 10 | 0 | 7 | 0 |
| September | 4 | 1 | 6 | 0 |
| October | 0 | 9 | 6 | 0 |
| November | 0 | 23 | 4 | 2 |
| December | 0 | 30 | 4 | 3 |
YOU SHOULD KNOW
Many people confuse weather and climate but they are different. Weather is the conditions of the atmosphere over a short period of time, and climate is how the atmosphere is over long periods of time.
Weather is how the atmosphere is behaving and its effects upon life and human activities. Weather can change from minute-to-minute. Most people think of weather in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure.
Climate is the description of the long-term pattern of weather in a place. Climate can mean the average weather for a particular region and time period taken over 30 years. Climate is the average of weather over time.