About 20,000 people sat in one spot in Southeast Washington on Sunday afternoon as dark clouds gathered overhead and drops of rain began to fall.

It appeared that a storm was brewing above Nationals Park, and that a downpour could be expected at almost any minute. From the ballpark, clouds could be seen to the north that seemed almost black in their storm-predictive darkness.

But as it turned out, those raindrops that did fall along South Capitol Street never amounted to anything, despite all the cloudy ominousness.

Washington was treated Sunday to a demonstration that history need not repeat itself. As recently as Thursday and Friday, we were deluged with a total of 2.79 inches of rain.

Many may have observed that the downpours of those two days came from skies not much different from Sunday’s. But Sunday told a different story.

At the official measuring station at Reagan National Airport, as of 9 p.m. the day’s precipitation entered the record books as a “trace” of rain.

In a way, Sunday seemed a sort of demonstration that a summer day in Washington can easily be punishing and unpleasant, but need not be that way.

Shielded by the darkly dramatic clouds, Washington experienced what appeared to be temperatures of the temperate sort. The official high at the airport was 82 degrees.

The low temperature in the morning was 67 degrees, average for the date. It showed that although an average temperature may not be the one that we can expect on a given day, actual and average do sometimes coincide.

The lack of measurable rain at National did not mean rain absented itself entirely from the area. In Martinsburg, W.Va., at the northwestern edge of our region, more than half an inch fell.

That confirmed that the day’s dark clouds, at times, did more than merely make threats.