The summary climate graph for Watertown, SD shows a selection of temperature, rainfall and snow minimum, mean and maximum measures over the course of a year. Click on each of the measures in the key to toggle them on and off.
The warmest month in Watertown Regional Airport, Watertown, South Dakota is July with an average high temperature of 84.3°F. The hottest day on record was May 10 1948 when the temperature hit 120.2°F. During January the overnight temperature drops to an average of 3.8°F with the lowest temperature of -35.1°F being recorded on February 9 1994.
The warmest days on record are:
| 10 May 1948 | 120.2°F |
| 25 Jun 1988 | 105.1°F |
| 10 Jul 1976 | 102.9°F |
| 30 Jul 2006 | 102.9°F |
| 31 Jul 1988 | 102°F |
The warmest months on average were:
| July 1976 | 92°F |
| August 1983 | 91.6°F |
| July 1988 | 90.8°F |
| August 1976 | 90.5°F |
| June 1988 | 90°F |
The coldest days on record are:
| 9 Feb 1994 | -35.1°F |
| 15 Jan 2009 | -34.1°F |
| 1 Jan 1974 | -33.2°F |
| 19 Jan 1985 | -32.3°F |
| 2 Feb 1996 | -32.1°F |
The coldest months on average were:
| February 1948 | 0°F |
| January 1982 | -10.4°F |
| January 1978 | -10.2°F |
| January 1977 | -9.1°F |
| January 1979 | -9.1°F |
The wettest month by average rainfall in Watertown, SD is June with an average of 2.7 inches of rain falling on 9 to 10 days.Although in May it typically rains on more days with 2.0 inches falling in 10 to 11 days. The driest month by average rainfall in Watertown, SD is December with an average of 0.4 inches of rain falling on 2 to 3 days. Although in January it typically rains on less days with 0.4 inches falling in 1 to 2 days
The wettest days on record are:
| 23 March 2009 | 1.5 inches |
| 4 March 1985 | 1.5 inches |
| 22 March 1979 | 1.1 inches |
| 12 March 1976 | 0.9 inches |
| 24 March 1987 | 0.8 inches |
The wettest months on record are:
| June 1977 | 8.6 inches |
| June 1990 | 6.8 inches |
| September 2010 | 6.6 inches |
| June 1993 | 6.3 inches |
| June 1980 | 6.3 inches |
The driest months on record are:
| February 1948 | 0 inches |
| March 1948 | 0 inches |
| April 1948 | 0 inches |
| May 1948 | 0 inches |
| June 1948 | 0 inches |