The season's first brief heat wave peaked at 96 degrees in Baltimore on Wednesday, missing one record but threatening another, and temperatures are expected to wane Thursday into the weekend.

Baltimore-Washington International Thurgood Marshall Airport, Baltimore's point of record, came 1 degree shy of matching a record dating to 1957. Wednesday morning's balmy start could be deemed a new minimum temperature record, with a low of just 76 degrees.

A ridge of high pressure over the region brought the year's first significant spike in temperatures into the 90s, a benchmark that had been reached only once in 2014 before this week. The Inner Harbor hit 95 degrees Wednesday.

With high humidity over the region — dew points hovered in the upper 60s throughout the day, an uncomfortable level — heat index values hit 100 degrees at BWI.

While the heat index has to reach 105 degrees or higher for local governments to declare heat emergencies and open cooling centers, Baltimore officials opened city pools in Clifton, Druid Hill and Patterson parks Wednesday, four days earlier than scheduled, because of the heat.

The heat was expected to fuel isolated thunderstorms Wednesday evening, with overnight lows forecast in the mid-70s. If temperatures did not drop below 75 degrees before midnight, the morning low was expected to set a new record for the highest minimum temperature on June 18 in Baltimore.

A weak cold front was expected to bring lower temperatures, albeit only slightly, on Thursday but more dramatically into the weekend. Highs Thursday are forecast in the lower 90s, with storms likely. After that, highs are forecast in the 80s, with more storm chances as the front stalls over the region for the weekend.

sdance@baltsun.com

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