Air Quality
Delaware's air quality has improved significantly since the 1990s, though industrial areas near Wilmington and coastal refineries still face occasional ozone alerts. PM2.5 levels remain near national norms.
Monitored days with good air quality
1990–2025U.S. EPA AirData, Annual AQI by County, all monitored Delaware counties.
Monitored days unhealthy for sensitive groups or worse
1990–2025U.S. EPA AirData, Annual AQI by County (AQI above 100).
| Indicator | Delaware | U.S. |
|---|---|---|
| PM2.5 concentration (µg/m³) | 7 | 8 |
- •Wilmington's industrial corridor has historically driven Delaware's air quality monitoring efforts.
Wildfires
Wildfires are rare in Delaware due to its humid climate and limited forested wilderness. Small brush fires occasionally occur in state forests during dry periods.
| Indicator | Delaware | U.S. |
|---|---|---|
| Annual area burned (hectares) | 50 | 1600000 |
- •Delaware's state forests use prescribed burns to reduce wildfire risk in a controlled manner.
Drought
Delaware receives ample annual precipitation and rarely experiences severe drought conditions compared to western states. Occasional short-term dry spells affect agriculture in Sussex County.
Area in drought (D1–D4), yearly average
2000–2025U.S. Drought Monitor (NDMC / USDA / NOAA), average of weekly maps.
Area in extreme or exceptional drought (D3–D4)
2000–2025U.S. Drought Monitor (NDMC / USDA / NOAA), average of weekly maps.
| Indicator | Delaware | U.S. |
|---|---|---|
| Annual precipitation (mm) | 1150 | 900 |
- •Delaware has never had a statewide drought emergency as severe as those seen in western states.
Water Usage
Delaware draws water from both groundwater aquifers and the Delaware River basin, with agriculture and public supply as the largest users. Daily withdrawals are modest given the state's small population.
| Indicator | Delaware | U.S. |
|---|---|---|
| Daily water use (million gallons) | 350 | 322000 |
- •The Delaware River provides drinking water to millions of people, including much of the state.
Emissions
Delaware's total CO2 emissions are among the lowest in the nation due to its small size and limited heavy industry. The state has committed to reducing greenhouse gases under regional climate initiatives.
Energy-related CO₂ emissions
1970–2021U.S. EIA State Energy Data System, all sectors and fuels (FRED EMISSCO2TOTVTTTODEA).
Transportation CO₂ emissions
1970–2021U.S. EIA State Energy Data System, transportation sector (FRED EMISSCO2TOTVTCTODEA).
| Indicator | Delaware | U.S. |
|---|---|---|
| Total CO2 emissions (MMT) | 10.5 | 4900 |
- •Delaware participates in the Regional Greenhouse Gas Initiative (RGGI) to cap power-sector emissions.
Climate Indicators
Delaware has a humid subtropical to humid continental climate with average annual temperatures around 13.5°C. Coastal areas face increasing flood risk from sea-level rise.
Average annual temperature
1895–2025NOAA National Centers for Environmental Information, Climate at a Glance, statewide January–December average.
Annual precipitation
1895–2025NOAA National Centers for Environmental Information, Climate at a Glance, statewide January–December total.
| Indicator | Delaware | U.S. |
|---|---|---|
| Average annual temperature (°C) | 13.5 | 12.9 |
- •Delaware is the lowest-lying state in the U.S., making it highly vulnerable to sea-level rise.