800' but this is my 4th summer here and we usually are within a degree or two of MDT's numbers for that year (average). Last August at this point we were banging an average temp HIGHER than MDT's numbers due to less rain/clouds and had close to 30 days of 90 or above just like MDT. The HIA has been extreme this year. We are 4 degrees lower on average than the last 3 Augusts here at this point so this has been a one time event. I remember doing daily posts last summer how we were pushing 90 by lunch over and over. Elevation is definitely playing a part as HGR is not as extreme to the cool as I am but something has been up this summer in the LSV HIA area. Like I said before, should MDT be warmer than Dulles? The heat in the urban areas has really stood out this summer.
Last year Dulles and MDT were .1 different so basically the same. This year Dulles is 1.6 degrees cooler than MDT! Hard to think it is just clouds and rain being the difference over almost 3 months.