Delaware's Climate
A look at the climate of the first state
Geography
Geography
The State of Delaware lies along the Atlantic coast of the United States, occupying the northern two-thirds of the Delmarva Peninsula. It is the second smallest of the United States with a land area of 1,982 mi². It is surrounded by water bodies including the Atlantic Ocean and Delaware Bay to the east, and the Chesapeake Bay to the west.
The State is situated in a transition zone between humid subtropical climate conditions to the south and humid continental conditions to the north. The moderating effects of the surrounding water bodies lessen temperature extremes compared to nearby interior locations. Even so, the State has a continental climate, with cold winter temperatures, hot summers, and ample precipitation throughout the year. However, annual precipitation amounts can vary greatly from one year to another.
This variation in annual precipitation can lead to differing snowfall amounts year to year, with some years receiving very little snow and other years seeing a higher snowfall.
Temperatures
Delaware's temperatures are moderate, with mean annual temperatures across the State ranging from 54°F in northern New Castle County to 58°F along the Atlantic coast of southern Delaware.
Despite the moderate annual averages, Delaware's seasonal temperatures vary significantly. Winter can bring about sub-zero temperatures while the summers can produce sweltering conditions. These seasonal temperatures may be made more extreme over the next century due to the effects of climate change.
The button below opens an interactive portal illustrating predicted climate projections into the near future up to the year 2100. General trends demonstrate a rise in average temperature in Delaware. Affected by a rapidly changing climate and sea-level rise, Delaware faces potentially damaging and life-threatening conditions, such as an increase in the frequency of flooding that disproportionately impacts Delaware coastal communities.
Check out the Delaware Climate Projections portal here:
The graph below shows Delaware's statewide mean annual temperature data for the years 1895 - 2020. There is a noticeable increase in the average annual temperature of about 0.24°F per decade, or about 3° F since 1895. The lowest year was 1904 with a mean annual temperature of 50.9°F while the highest value was in 2012 with a value of 58.5°F. You can interact with the graph below here to pick other data and other periods of record to explore.
Delaware Average Temperature NOAA National Centers for Environmental information, Climate at a Glance: Statewide Time Series, published June 2022, retrieved on June 11, 2022 from https://www.ncdc.noaa.gov/cag/
Precipitation and Storms
Precipitation and Storms
Delaware's geographical features and location on the east coast of the United States presents both beautiful views and climate challenges.
Precipitation and Storms
Proximity to the Atlantic Ocean enhances winter and spring nor-easters that can drop heavy snow, heavy rain and cause coastal flooding and inland flooding across the State. Autumn tropical systems are accompanied by high winds, coastal flooding, and heavy rainfall. Spring and summer severe thunderstorms can cause damage associated with high winds, hail, and even tornadoes.
Precipitation and Storms
The frequency and/or the intensity of severe weather events may be modified by changes in climate. As evident in the temperature graph previously displayed, annual temperatures in Delaware have risen substantially since 1895 and are projected to continue trending upward as seen here . The rising temperatures and increasing moisture content of the atmosphere will almost certainly impact the character of severe weather across the State.
Delaware's Beauty
Despite these challenges, Delaware's coastal location is one of the defining environmental attractions of the state, attracting many tourists to popular areas such as Rehoboth Beach or Cape Henlopen.
Delaware Climate Normals
For U.S. Climate Normals, see here .
Northern Delaware
Wilmington Porter Reservoir | USC00079605
CEMA
CEMA is an environmental data services center within the College of Earth, Ocean, and Environment (CEOE) at the University of Delaware. CEMA provides the following primary services to the state of Delaware and its citizens:
- Real-time Monitoring and Historical Environmental Data Repository
- Weather and Climate Outreach and Expertise
- Engineered Environmental Data Products and Solutions
CEMA houses the Office of the Delaware State Climatologist, Delaware Environmental Observing System, Delaware Environmental Monitoring and Analysis Center, and the University of Delaware’s Satellite Receiving Station. CEMA serves as the most comprehensive observed environmental data resource for Delaware.
Center for Environmental Monitoring and Analysis | cema.udel.edu
Delaware Environmental Observing System (DEOS) | deos.udel.edu
