Takoma Park's Independence Day committee scrapped its 137th annual celebration, canceling Saturday's 10 a.m. downtown parade and the 6-9 p.m. street party.
Upper-90s to low-100s temperatures through Sunday drove the decision, with "feels like" readings near 110 and a July 4 heat index forecast of at least 105.
Tara Marie Egan said marching and waiting outdoors would leave participants without practical ways to rest or cool down, making the event unsafe and irresponsible to hold.
Montgomery County has declared a Heat Emergency through the holiday weekend, while the National Weather Service issued an extreme heat warning for Friday and a watch for Saturday.
The county also pushed fireworks start times in Kensington and South Germantown to 7:30 p.m., as health officials urged residents to hydrate and avoid peak outdoor heat.