Triple-digit temperatures could hit D.C. as heatwave extends east

• Highs are expected to rise near or hit triple digits tomorrow through and Saturday. The heat index — what it will feel like when factoring in humidity — is forecast to be near 110° by the end of the week.

The big picture: The heatwave roasting much of the U.S. for weeks is expanding its reach to the Great Basin and parts of the Rockies, and will eventually extend eastward across the Plains, Midwest, and East Coast by the end of the week, Axios' Andrew Freedman writes.

• Heat alerts lit up yesterday from South Florida northwestward to Montana.

Context: D.C. last hit 100° in August 2016.

• Average July temperatures are 81° for the region, according to the National Weather Service.

Between the lines: The extreme heat in the U.S. is one of three major events occurring simultaneously worldwide, and July is on track to be the globe's warmest month on record.

• The longer this extreme heat event lasts, the greater the human and economic toll will be.

Zoom in: Unhoused residents are among the most at risk of extreme heat.

• About 15% of unhoused residents in D.C. have a chronic health condition and more than 30% are over the age of 55, per a recent survey.

Be smart: The city encourages residents to check on seniors, unsheltered residents, and other vulnerable groups during extreme heat events. You can request free transportation to a cooling center by calling 202-399-7093 or dialing 311.