Maryland weather: The year's first heat wave is here, and it's bringing poor air quality

Baltimore's longest stretch of 90-degree heat since last July is here.

Temperatures are forecast to reach the 90s for a third straight day Wednesday, and even hotter weather approaching the mid-90s is forecast later this week.


The stagnant hot, humid air over the region is also contributing to poor air quality. A "Code Orange" Air quality alert is in effect Thursday, indicating unhealthy conditions for sensitive groups, including children, the elderly and people with heart or lung illnesses.

Heat and sunlight trigger chemical reactions with pollution in the atmosphere that create lung-irritating smog. Without winds to dissipate the smog, air quality can decline to reach hazardous levels.

Advertisement meteorologists said the season’s first sustained dose of heat can be a shock to the system, triggering heat-related illnesses, and the shock of higher energy bills.

“There will also not be too much cooling at night, especially in urban areas, resulting in higher electric bills as cooling demand increases around the clock,” AccuWeather Meteorologist Ryan Adamson said.

Temperatures around Baltimore are forecast to reach the lower 90s Wednesday and Thursday, could approach the mid-90s on Friday, and again reach the lower 90s Saturday. Little relief is in the forecast beyond that, with temperatures in the mid- and upper-80s going into next week.

At Baltimore-Washington International Thurgood Marshall Airport, temperatures reached 91 degrees Monday and Tuesday.

The last time temperatures hit the 90s on at least six consecutive days came last June and July. BWI reached the 90s on seven straight days from June 29 through July 5.

Average highs this time of year are in the mid- to upper-80s. Baltimore’s record highs in late June and July are mostly in the triple digits.