Given that September had pulled off a convincing impersonation of August, if the chill and abject dreariness this week has stimulated nothing more than your appetites for carbohydrates and lethargy, consider yourself normal.

"This is unwelcome and unexpected," psychiatrist Norman I. Rosenthal - who literally wrote the book on the subject, The Winter Blues, and is credited with being the first to use the term seasonal affective disorder to describe a condition wrought by the change of seasons - said Friday. "There's a shock and denial."

Rosenthal, who practices in the Washington area, which has gone toe-to-toe with the Philadelphia region for gloom, reassured that a certain reluctance to leave one's bed is a common response to the rapid loss of light this time of year - when the sun gets up later, goes to bed earlier, and shines more obliquely in between.

But the light deprivation and the cooldown of the last few days have been exceptional, he noted, especially in contrast to the warmth and dryness of the month.

After the warmest August locally, September was the fifth-warmest in Philadelphia dating to 1874, with an average temperature of 73.5 degrees, and five days with highs of 90 or better. It also was a month in which - before Tuesday - rain fell on only two days.

In fact, this week the nation's official drought agency designated the entire region as either "abnormally dry" or in "moderate drought." Don't be shocked if that changes next week.

The rains this week have been generous and widespread - about 1.75 inches in Philadelphia since Tuesday, with several inches in lower Delaware, according to the National Weather Service. The showers and overall dreary weather are due to continue possibly through Monday.

The AWOL sun might make a cameo Sunday, but with persistent onshore winds, a harvest of cloudiness could persist through next week, said Brett Anderson, a meteorologist with AccuWeather Inc.

Since Sept. 19, the region has been losing two minutes and 36 seconds of daylight per day - the time between sunrise and sunset - the biggest daily loss of the year. Starting next week, however, the loss rate slows gradually until it approaches zero around the winter solstice.

Still, the days will be getting shorter, and some of our readers might be gaining a pound or two.

In what was considered a landmark study when he was with Georgia State University, John M. de Castro observed 300 subjects and concluded that each consumed 222 more calories per day during the fall months, September, October, and November, compared with the other seasons. The Thanksgiving period was excluded.

While heartier appetites and a certain abhorrence of activity are par for the season, Rosenthal points out that for about 5 percent of Americans with seasonal affective disorder, the loss of light is a serious impairment. He said that about 15 percent have a less-serious variant, the so-called winter blues. But those blues don't always wait for winter.

"I think it's very good to realize that darkness hits when it chooses to," he said, "and you can't go by the calendar."