Record-breaking temperatures persist across Delaware
DELAWARE – Friday, June 21, 2025, 9:00 AM (ET) – The heat dome that has settled over much of the Mid-Atlantic and Northeast is now producing extreme heat across Delaware, with temperatures well into the upper 90s°F (35–38°C) and heat index values topping 105°F (over 40°C) in several locations. This dangerous heat wave, which began earlier this week, is expected to persist through the weekend, pushing humidity levels to oppressive levels and raising growing concerns for public health and infrastructure.
Excessive heat warning in effect
The National Weather Service has issued an Excessive Heat Warning for New Castle, Kent, and Sussex Counties, in effect through Saturday evening, with possible extensions into Sunday depending on how the system evolves. Highs today across Wilmington, Dover, and Rehoboth Beach are forecast to reach 98°F (36.7°C), with “feels-like” temperatures surpassing 110°F (43.3°C), particularly in urban areas with limited overnight cooling.
Unrelenting heat amplified by stagnant air
This heat dome phenomenon, a persistent ridge of high pressure, continues to trap hot, moist air over the region. Winds remain light, and skies are mostly clear, allowing maximum solar heating. With nighttime lows hovering around 78°F (25.5°C) in the cities, there is little relief after sunset, keeping indoor temperatures elevated and stress on cooling systems high.
Impact on health, energy, and transportation
Officials in Delaware have reported an uptick in emergency calls related to heat exhaustion and heatstroke, particularly among outdoor workers, elderly populations, and those without air conditioning. Utility companies across the state are urging residents to be mindful of electricity usage, as power demand approaches seasonal peaks. Meanwhile, transportation departments are monitoring roadways and rails for signs of heat-related buckling.
Weekend outlook: Continued high heat, slight relief next week
Forecast models suggest that the heat dome will begin to weaken gradually by Monday, with a cold front possibly moving into the region by Tuesday, bringing thunderstorms and slightly cooler air. Until then, the heat wave will maintain its grip on Delaware, with Saturday highs again near 97°F (36.1°C) and Sunday only marginally cooler.
The intensity and duration of this event make it one of the most significant June heat waves in Delaware’s recorded history.
