Occurring only once every four years, weather records for February 29 are necessarily limited. For example, the number of leap days on record at Dulles airport is just 13, since observations began there in 1963. Thus, it’s not surprising that today’s old rainfall record of 0.51” from 1968 was easily bested today. The airport has received 0.99” so far.
Baltimore Washington International’s (BWI) records date back farther, to 1871, putting the leap day sample size at 34. Its previous record rainfall was 0.92” from 1892, a bit more impressive. But still, today’s total of 1.03” (so far) passed it.
Reagan National Airport, on the other hand, has received 1.12” - quite a bit shy of the rainfall record for the date of 1.61” from 1892. Its records also began in 1871 (at a different observing site), also producing a sample size of 34. More rain showers are likely through this evening. but picking up another 0.4” may be a stretch.