* Extreme heat impacts roads, rails, electronics and more *

For the sixth time this summer, Washington, D.C. reached at least 100 degrees. We may tack on a 7th Wednesday, with higher humidity levels to boot. Late day thunderstorms herald the start of a gradual cooling trend Thursday.

Through Tonight: A lack of cooling storms or much of a breeze make it one of the more suffocating evenings of the summer. Lows struggle to reach 80 in the city. Low-to-mid 70s are as “cool” as it gets in the outer suburbs. Winds are from the southwest around 5 mph.

Wednesday: Hot and oppressively humid. A heat advisory goes into effect at 11 a.m. and continues until 9 p.m. High temperatures head back up to near 100, with heat indices around 105. Late in the afternoon, but more likely into the evening, showers and thunderstorms are possible. These storms are likely to produce heavy rain and dangerous lightning. Damaging winds are a possibility in some of the storms. We will keep you posted.

See Matt Rogers’ forecast through the weekend. And if you haven’t already, join us on Facebook and follow us on Twitter. For related traffic news, check out Dr. Gridlock.

100 degree days: This year’s 6 100+ days ties for third most on record in one year. The recordholder remains 1930 with 11 such days. In the last three summers, we’ve had 15 100+ days (5 in 2011, 4 in 2010). Consider that from 1993-2009, we had just 17 such days. (Information courtesy Ian Livingston and Justin Grieser)