Temperatures reached 98 degrees Wednesday afternoon at Baltimore-Washington International Thurgood Marshall Airport, making it the region’s hottest September day since 1991.And on Thursday, it got nearly as hot. BWI temperatures reached 97 by 2 p.m., according to the National Weather Service.That broke a record for Sept. 12 in Baltimore, 96 degrees set in 1931. The temperature at BWI dropped to 94 degrees by 3 p.m., but bounced back up to 96 by 4 p.m.Meteorologists warned storms are likely Thursday evening, fueled by the heat and humidity, and some could be severe. Damaging winds are expected to be the main threat.Until Wednesday, temperatures hadn’t reached 98 at BWI in September since Sept. 16, 1991. The record for Wednesday’s date is 100 degrees, set in 1983.The hottest September temperature ever recorded in Baltimore is 101 degrees, in 1881. Average September highs are in the 70s and lower 80s.Wednesday’s heat at BWI was somewhat of an anomaly across the region. At the Inner Harbor, temperatures reached 93 degrees. BWI is the region’s point of record.National Weather Service meteorologists said it was possible the downtown reading was so much lower than the BWI reading because the harbor waters can help keep the air cooler.After cooling to the 60s and 70s Friday, temperatures are expected to reach the mid- to upper 80s this weekend into early next week.