This weekend, which many view as the unofficial start of summer, a time of leisure, pleasure and relaxation, will not even be over before a reminder arrives of summer’s possible hazards, in the form of National Hurricane Preparedness Week.

President Obama’s proclamation Friday of the preparedness week came shortly after the federal government predicted an active Atlantic hurricane season this year.

The Washington region has largely escaped the full fury of recent hurricanes, but past weeks have demonstrated the region’s acquaintance with several forms of nature’s dangers. These have ranged from flash floods to sinkholes to an earthquake and tornadoes.

As a prelude to the Memorial Day weekend, and the informal onset of summer, Friday was not overly benevolent.

It was cloudy. It was chilly. It was windy. Whatever pleasures Friday provided, they did not seem to spell summer.

The high temperature for the day at Reagan National Airport was 67 degrees — 11 degrees below the normal high.

And the mercury hit that not particularly lofty level at 12:30 a.m., an unusual time for it.

By 10:40 a.m. the mercury had fallen to 55 degrees. For the rest of the day it never rose above 60, and clouds and wind only enhanced the feeling of fall.

By 5 p.m. Friday, the top wind was clocked at 29 mph, with a gust of 38. The wind apparently played direct and indirect roles in preventing many Washington region residents from full enjoyment of the weekend.

For a time Friday, rain and strong winds above the Chesapeake Bay prevented one of the bay bridges from carrying traffic in both directions. That reduced the number of lanes available for eastbound travel, toward the Atlantic beaches.

Three eastbound lanes became available by 3 or 4 p.m., but “MAJOR DELAYS” faced travelers headed east after work on Friday, according to Twitter messages from state transportation officials.

At one point, an 18-mile backup was reported. Travel after 10 p.m. was recommended.

The rain over the bay early Friday came from the same fierce Thursday night storm that caused flash flooding in parts of Maryland and that, according to highway officials, prompted a rescue from high water in the Hanover area.

A little less than one-fifth of an inch of rain fell into the gauges at National, but Baltimore reported almost an inch. Just .01 inch less. Dulles recorded 0.49 inches.

Friday’s winds seemed strong but were less powerful than those produced by the two tornadoes recorded in the Washington region last month.

One, in the Fredericksburg area on April 19, had peak winds of 90 mph, according to the National Weather Service. The other, in the Largo area on the same evening, was weaker.

These provided mere hints of the deadly and destructive power that tornadoes have demonstrated elsewhere, but they also showed that Washington lacks tornado immunity.

The earthquake aftershock that occurred this month appeared also to be a kind of reminder. It occurred just after 7 on the morning of May 15. It was measured at magnitude 2.3 and was centered about 5 miles south-southwest of Louisa, Va.

The U.S. Geological Survey tied the aftershock to the historic magnitude-5.8 earthquake that occurred in the same general area a little less than two years ago. The area of origin falls within a seismic zone that exists in Central Virginia, the survey said.

The shaking of the ground on May 15, the survey said, was an aftershock from that quake, one of more than 450 aftershocks that have been recorded since the big 2011 quake.

The survey said more than 50 of the aftershocks were large enough to be felt, and 38 were at least the size of the May 15 shock.

The survey’s report on where the May 15 aftershock was felt indicated that one person in the immediate Washington area had told of feeling it. The report came from Hyattsville, the USGS said.

Scientists expected that the aftershocks “will continue for many months,” the survey said.

Meanwhile, the recent completion of the scaffolding around the Washington Monument provides a vivid visual symbol of the August 2011 quake. The scaffolding is required for repairs caused by that quake.

The precise cause of the sinkhole that opened in downtown Washington has not been specified. But it nevertheless appeared to reflect to some degree the geological conditions beneath the pavement at 14th and F streets NW.

Restrictions on travel by automobile in that area apparently may continue for some time, while repairs are carried out.

In a message sent by the District’s transportation department Friday, officials said the closures “may go thru 5/27.”

However, officials said they planned to make a virtue of necessity. “While these closures continue we plan to resurface stretches of the now closed area,” the DOT said online.

If not much warmer than Friday, the rest of this weekend should be brighter, according to the National Weather Service forecast.

It called for Saturday to be sunny, with highs in the upper 60s. Winds would persist, however, with gusts as high as 30 mph, the weather service said.

Sunday highs were expected to climb into the lower 70s, with winds in the 10 to 15 mph range.

On Monday, the forecasters said, it would be sunny, with high temperatures in the middle 70s.

In Friday’s proclamation, the president said “it is never too early” to get ready for this year’s hurricane season.

He urged families to discuss what to do in a disaster and develop a plan that everyone knows.