Delaware heat advisories
There are no heat advisories in Delaware right now. The last one was issued on September 3, 2026.
Hot and humid conditions will raise the heat index enough to cause heat illness for people without cooling.
Updated from the National Weather Service · lists refresh hourly; the live map loads current alerts directly from the NWS
Active heat advisories in Delaware
None right now. Other active alerts in Delaware: 1 (see the Delaware alerts page).
Heat Advisories in Delaware by year
Delaware averaged 6.7 heat advisories per year from 2016 to 2025, and has had 9 so far in 2026. The most recent was issued on September 3, 2026.
Counties with the most heat advisories
| County | 2016–2025 |
|---|---|
| New Castle County | 51 |
| Sussex County | 35 |
| Kent County | 34 |
What a heat advisory means
A heat advisory is issued when the heat index, which combines temperature and humidity, is expected to reach levels that can cause heat exhaustion or heat stroke. Thresholds vary across the country because people adapt to their local climate: offices in the Gulf Coast use higher values than those in the Northeast or Pacific Northwest.
More about heat advisories and the national map →
What to do
- Drink plenty of water and limit strenuous activity outdoors.
- Spend time in air conditioning; public libraries and cooling centers can help.
- Never leave children or pets in parked cars.
- Learn the signs of heat exhaustion and heat stroke.