Prepare to turn up the proverbial stove... In a summer that has been mostly defined by swings in temperatures, changes in patterns, and no dominant force of above or below average temperatures, the last few days have been one thing : hot. And it's forecast to continue through the end of the week and into the weekend; with the climax of the heat coming on Friday afternoon. Heat index values on Thursday and Friday are expected to exceed 105 degrees easily, but on Friday they may climb towards 115 degrees at times thanks to 75 degree dew points. The heat will be unbearable, and even dangerous at times. These type of heat index values are not common in our part of the nation--in fact, even last summer's record heat did not have such values as the dew points were much lower. In fact, the National Weather Service has issued an Excessive Heat Watch for the area for both Thursday and Friday afternoons. Featured image: NAM model showing forecast high temperatures of over 102 degrees on Friday afternoon.

Wondering what the heat index indicates? ...Wonder no more. The heat index is a calculation that uses both the temperature and either the Dew Point or Relative Humidity to determine how "hot" the air really is. In other words, instead of telling us the temperature of the thermometer, it tells us how hot the air really feels to our bodies. Heat index values over 100 degrees are considered very hot--values over 110 considered dangerous--and values over 115 considered extreme. The heat index values advertised for this weekend, with the 100 degree temperatures and 75 or higher degree dew points, would be extreme..or over 115 degrees. For reference on the chart to the right--relative humidity values with the 100+ degree temperatures and 75+ degree dew points would be around 44-45%. Featured image (left): Heat index curve showing the severity of the heat index.

Article written July 19th, 2011 at 4:21pm. Looking for a forecast? See New York Metro Weather's Long Range Forecast for the remainder of the week into the weekend, or view our Technical Forecast Discussion for the more serious weather enthusiasts. Also, check out our new Forecast Overview tab. For up to the minute details on forecasts, watches, warnings, and alerts, follow us on Twitter and Facebook.