Extreme Heat

During periods of extreme heat, the City of Boston may declare a heat advisory or emergency and open cooling centers or extend pool hours. The City asks that you check on your neighbors, especially the elderly to ensure they are okay. You can call 311 or review our heat resources for additional up-to-date information.  

Heat Information

Weather Terms

  • Heat Wave: Prolonged period of excessive heat, often combined with excessive humidity.

  • Excessive Heat Watch: Conditions are favorable for an excessive heat event to meet or exceed local Excessive Heat Warning criteria in the next 24 to 72 hours.

  • Excessive Heat Warning: Heat Index values are forecast to meet or exceed locally defined warning criteria for at least 2 days (daytime highs=105-110° Fahrenheit).

  • Heat Advisory: Heat Index values are forecast to meet locally defined advisory criteria for 1 to 2 days (daytime highs=100-105° Fahrenheit).


  • Install window air conditioners snugly; insulate if necessary.

  • Check air-conditioning ducts for proper insulation.

  • Install temporary window reflectors (for use between windows and drapes), such as aluminum foil-covered cardboard, to reflect heat back outside.

  • Weather-strip doors and sills to keep cool air in.

  • Cover windows that receive morning or afternoon sun with drapes, shades, awnings or louvers. (Outdoor awnings or louvers can reduce the heat that enters a home by up to 80 percent.)

  • Keep storm windows up all year.

  • Sun in Clear Sky (200)

    Heat Emergency Tips & Facts

    View our complete list of tips and facts. Please contact the city at 311 at any time with questions or concerns.

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  • Family Preparedness Planner

    Family Preparedness Planner (Flash required)

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