Delaware Annual Temperatures and Records

City

Avg High Temp

Avg Low Temp 

Avg Annual Temp

Avg # days > 90F Avg # days < 32F  Record High Temp Record Low Temp
Dover 66.5 47.2 56.8 28 85 102 -5
Wilmington 63.5 45.1 54.4 19 98 102 -14
  • Delaware annual average temperature - 55.27 degrees, 16th warmest state in the U.S.
  • Record Hottest year in Delaware - 2012 / Avg temperature 58.81 degrees
  • Record Coldest year in Delaware - 1904 / Avg temperature 51.35 degrees
  • Delaware average Summer temperature (June, July, August) - 74.2 F degrees, 16th warmest U.S. summer state
  • Delaware average Winter temperature (December, January, February) - 36.1 F degrees, 34th coldest U.S. winter state

Delaware Temperature Records

  • Hottest temperature ever recorded: 110 F, Millsboro, southern Delaware, 7/21/1930
  • Coldest temperature ever recorded: -17 F, Millsboro, southern Delaware, 1/17/1893
  • Hottest location ranked by highest average annual temperature: Dover, central Delaware, 56.5 F
  • Coldest location ranked by lowest average annual temperature: Wilmington, northern Delaware, 54.3 F
  • The summer of 2010 was the warmest summer on record for the state of Delaware since 1895, with an
    average temperature of 78.1 degrees.

The climate of Delaware is "humid temperate" with hot summers and mild winters. The mean annual temperature ranges from 55 F in New Castle County to 56 F over Kent and Sussex counties.

The winter climate is intermediate between the cold of the Northeast and the mild weather of the South. Extremely cold air masses from the interior of the continent are moderated somewhat by passage over the Appalachian Mountains. The average frost penetration ranges from about five inches in southern Delaware to about 10 inches in northern Delaware. Summer weather is characterized by considerable warm weather, including at least several hot, humid periods. However, nights are usually quite comfortable. The average length of the growing season based on minimum temperatures higher than 32 F, ranges from about 175 to 195 days.

The lowest temperature of record for Delaware is -17 F, at Millsboro on January 17, 1893, came in a month which is quite likely the coldest ever known in Delaware and surrounding areas. Noteworthy is the fact that Millsboro also has the distinction of having the highest temperature, 110 F, which occurred on July 21, 1930. An extended heat wave during the period July 18-31, 1930, brought maximum temperatures of 100 F, or higher, on three to four consecutive days at many places.

Temperatures of 90 F or higher occur on 15 to 20 days per year on the average in coastal areas and on 25 to 30 days at inland points. The fist day with a 90 or higher temperature occurs in May or early June. An average of one day with a maximum temperature of 90 or higher occurs in May. The last day with a maximum temperature of 90 or higher usually occurs in September or infrequently in early October. September has an average of one to two days per year with a maximum temperature of 90 F or higher. The average number of days per year with a minimum temperature of 32 F or lower varies from 90 to 100 days for coastal locations to 100 to 110 days at inland points. Temperatures of 0 F or lower occur in the winter months.

 

Delaware precipitation averages and extremes, precipitation and temperature data for all U.S. states and Top 10 U.S. climate extremes
Data source: National Climatic Data Center