Rain fell throughout the Washington area yesterday morning in amounts that ranged from showers that brought less than half an inch to some spots to deluges of nearly three inches on the southwestern fringes of the region.

High water closed roads in Fauquier County where the National Weather Service reported that 2.7 inches of rain fell. A police dispatcher in Warrenton said that her own home rain gauge measured four inches in a seven-hour period.

The 2.70 inches reported in Fauquier County and also in Haymarket, in Prince William County, exceeded the amount that had fallen in the District through the first 29 days of August.

A substantially below normal 2.06 inches had been recorded up to yesterday at the official measuring station at National Airport. The .69 inches that fell there yesterday brought the reading to 2.75 inches, still more than an inch below normal.

Meanwhile, with the month ending at midnight tonight, forecasters noted that this has been one of the coolest Augusts in years. So far the temperature has reached 90 degrees or above only five times this month, the fewest since 1972, when the mercury reached that figure only three times.