Mount Vernon Seasonal temperature break down - The average median temperature March through May is approximately 61°F with highs averaging at 71°F and lows averaging at 52°F. June through August has an approximate average median temperature of 76°F with highs averaging at 86°F, lows typically average at 67°F. Average median temperatures September through November average out at 63°F, high temperatures average out at 74°F and lows average at 53°F.
The average median temperature December through February is approximately 46°F with highs averaging at 56°F, lows average out at 40°F.
The average Mount Vernon annual median temperature averages out at approximately 61°F. The coldest month in Mount Vernon is January with a median temperature of 41°F, the average high for the month of January is 51°F with an average low of 35°F. The hottest month in Mount Vernon is September with an approximate median temperature of 77°F, the average high for the month of September is 90.2°F with an average low of 66.8°F.