August forecast

Climate forecasters are calling for a cool weather pattern in the eastern U.S. to start off August, with about a 40 percent chance of cooler-than-normal temperatures for Maryland. (Climate Prediction Center / July 30, 2013)

Humidity has been at fall-like levels at the start of this week in the Baltimore area and much of the East, and while it could creep up starting Wednesday, an overall cooler weather pattern is forecast to carry into the first half of August.

Dew points were hovering around 50 degrees for a second straight day in Baltimore on Tuesday -- a level more common in September or October. Dew points factor in both temperature and humidity levels, and typically sit in the mid-60s or higher during summer in Baltimore.

Temperatures in the lower 80s, meanwhile, mean it's slightly below normal for this time of year, when highs are in the upper 80s, on average.

The short-term forecast calls for temperatures to remain below the mid-80s through the weekend. Dew points could again rise into the 60s, but are not expected near levels in the mid-70s seen in the heat earlier this month.

A pattern is developing in which what meteorologists call a "trough" will form over the eastern U.S. In that situation, cool air from Canada spills southward, pushing the humid tropical warmth southward as well. AccuWeather forecaster Henry Margusity discusses it in this video blog.

Climate forecast maps illustrate the pattern. The Climate Prediction Center is forecasting strong chances of cooler-than-normal temperatures for the eastern half of the country through nearly the first two weeks of August.

Those climate forecasts make broader predictions, so expect a cool start to the month on average, but not every day.

Typical heat is still likely to pop up in the last month of summer and balance things out, though. Climate forecasts for the full month of August show the month as having equal chances of above- or below-normal temperatures.