Rain fell in torrents Tuesday during a gray day of fog and mist that was one of the Washington region’s wettest days of the year.

Rainfall at Dulles International Airport set a record for the date. The 2.26 inches measured by 5 p.m. far outstripped the previous mark of 1.18 inches, set on Oct. 2, 1973.

Fog is expected to persist Wednesday morning, which could affect traffic. The National Weather Service said morning visibilities could be cut to a quarter-mile or less at times.

Visibility was down to about a quarter-mile late Tuesday night at Dulles International Airport. At one point Tuesday night, it was less than 1,000 feet at Andrews Air Force Base, according to Weather Service reports.

Rain and fog forced a plane carrying Vice President Biden to land at Dulles instead of Andrews. The plane, coming from North Carolina, circled Andrews for 45 minutes before heading to Dulles, the Associated Press reported.

Heavy rain, particularly in the northern and western parts of the region, made for wet travel Tuesday morning, with rising water closing some roads in outlying areas.

“Harrowing drive down from Damascus,” one motorist said on The Washington Post’s Capital Weather Gang blog. Maximum speeds were 25 mph at about 11 a.m., the motorist said, on roads that were “all seriously ponding.”

Part of Zion Road in the Laytonsville area of upper Montgomery County was reported closed by four to six feet of water on the roadway, according to the Weather Service, citing information from the county’s 911 call center.

Parts of Beach Drive in Garrett Park, Frederick Road in the Germantown area and Game Preserve Road in the Gaithersburg area also were plagued by rising waters.

Heavy rains were reported in the western Virginia suburbs. “Wave after wave of very heavy downpours” soaked western Loudoun County, said another report to the Capital Weather Gang.

The drenching at Dulles was the greatest amount of rain recorded there all year. The official measuring station had not recorded as much as two inches on any previous day.

In addition, the record-setting rainfall at Dulles outstripped all of the daily measurements made this year at Reagan National Airport.

The total rainfall measured Tuesday at National as of 5 p.m. was 0.43 inches, far below the Oct. 2, 1976, record at National of 1.74 inches.

Not only was Tuesday wet, it was also foggy. In the afternoon, the pyramidal top of the Washington Monument, a little more than 500 feet above ground, was all but hidden in a blanket of gray.

For all their intensity, Tuesday’s rains still left the total rainfall for the year below normal, as measured at the official Weather Service stations.

At Dulles, total precipitation for the year amounted to 25.03 inches — more than seven inches below the normal figure of 32.13 inches.

At National, the 23.43 inches recorded for the year was 6.9 inches, or about 23 percent, less than normal.