The name Indian Summer has nothing to do with this year's World Series (Cleveland Indians and Atlanta Braves), nor does it have anything to do with the Washington Redskins playing football at this time of the year. Indian Summer is a catchy description of a pleasant weather event. In folklore, one explanation of Indian Summer is that the early European settlers noticed that the summer-like weather, often experienced in the autumn, was a time when the Native Americans took advantage of the fine weather to store their crops and to ready their lodges for the coming winter. According to most definitions, Indian Summer can only occur after the first frost of the Autumn, when a period of delightful weather happens between episodes of cooler weather. Many parts of Maryland experienced some frost earlier in the week, so for the past few days we've officially been enjoying Indian Summer.

For the related question about weather phenomena in September and October, the answer I was looking for is fog. When the nights get longer in the fall, and the humidity is still high, and the ground is still warm, fog is likely to form in the early morning hours if the nighttime sky is clear. It is the nocturnal cooling of the ground by escaping terrestrial radiation (energy the Earth has absorbed during the course of the day) that chills the layer of air above the ground and produces a cloud at the surface (fog). Since clouds, like a blanket, keep most of the energy from escaping, on cloudy nights the temperatures do not become cool enough for fog to form. The temperature at which fog forms and at which dew occurs is called the dew point. If the air is humid, the dew point temperature is higher than it would be in dry air.

The weather in Maryland this week has been warm, but not really hot, with cool night and clear skies. However, this is not technically considered to be Indian Summer weather. Why?

Also, in Sept. and Oct., what weather phenomenon do we usually experience more than any other time of the year?

10/16/95