Humidity surging, but forecast to dissipate by the weekend

  • Andrea LaSane carries 8-year-old Tony Hunt through a sprinkler.
Andrea LaSane carries 8-year-old Tony Hunt through a sprinkler. (Amy Davis, Baltimore Sun…)
July 10, 2013|By Scott Dance, The Baltimore Sun

Humidity is at or near its highest levels of the summer in the Baltimore area, but relief is in sight as the weekend approaches.

The dew point reached a stifling 74 degrees by 11 a.m. at both Baltimore-Washington International Thurgood Marshall Airport and at the Inner Harbor, with temperatures only a few degrees warmer in the lower 80s.

Dew point takes into account both the temperature and the relative humidity and gives a straightforward picture of how hot it feels -- anything above the mid-60s feels sticky, while the mid-70s is pretty oppressive. It is a measure of the temperature at which moisture in the air would condense into dew on grass or fog in the air.

Detailed records of dew points are not kept, as they are with temperature and precipitation. But a daytime 74-degree dew point is not far off from the highest humidity levels recorded in Baltimore.

A dew point of 81 degrees has been observed three times since 1962, according to Steven Zubrick, science and operations officer with the weather service's Baltimore/Washington forecast office in Sterling, Va. They occurred June 15, 1981 at 6 p.m., Aug. 5, 1989 from 2-4 p.m., and July 24, 1999 at noon.

Higher dew points may have been recorded before 1962, and data was also missing for 1977, Zubrick said.

Regardless, the message is the same: It feels quite humid in Baltimore on Wednesday, despite a relatively mild air temperature.

A reprieve is forecast to arrive Friday. Dew points are forecast to drop into the lower 60s, and even possibly the upper 50s, to end the work week. They could reach the mid-60s Saturday and upper 60s by Sunday.

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