www.baltimoresun.com/news/weather/weather-blog/bal-wx-is-this-an-indian-summer-20130911,0,7261626.story

baltimoresun.com

Is this an 'Indian Summer'?

By Scott Dance, The Baltimore Sun

11:25 AM EDT, September 11, 2013

Advertisement

Since people like to think fall is upon us once Labor Day passes and the humidity drops, making this week's burst of heat an Indian Summer. But there is a technical definition of the term, and this week's weather doesn't meet it.

Sources from the National Weather Service to the Old Farmer's Almanac suggest that an Indian Summer has some very specific characteristics:

This week's weather meets almost none of those criteria.

Sure, it's a little hazy, with some clouds, but there is a slight southerly breeze of 5-10 mph.

For now, it's dry, but thunderstorms are possible anytime this kind of heat and humidity hang over the region, and they're most likely on Thursday. And besides, just 0.02 inches of rain have fallen so far this month at Baltimore-Washington International Thurgood Marshall Airport, after just over an inch fell in what was the 10th-driest August on record.

And despite a taste of crisp autumn weather so far this month, with a few days dropping into the 50s overnight and low humidity, the region has not come close to its first frost. Last weekend, temperatures were forecast to take their first dip into the 40s but missed that mark across the region.

After all, it's still technically summer for another week and a half. The autumnal equinox is Sept. 22, and actually, according to the Old Farmer's Almanac, an Indian Summer must occur between St. Martin's Day (Nov. 11) and Nov. 20 -- not a broad window for a term we use pretty loosely these days.