There is no doubt that the heat we have seen recently and will see again Wednesday afternoon is significant, especially in mid-September. High temperatures were in the 90s for nearly everyone in the Tri-State on Tuesday:

With temperatures in the 90s and dewpoints in the 70s, maximum heat indices from local, reliable weather stations were in the 100-105° range Tuesday afternoon.

Is it rare to see 90°+ heat in September in Cincinnati? We average 2 90°+ days each September in Cincinnati, but it’s mainly feast or famine for 90°+ heat in September in the last several years:

On average (1871-2012), our last 90°+ day of the year in Cincinnati is September 9th. The 30-year-average for the last 90°+ day of the year is August 29th. The window for the last day making it to 90° is quite large, however:

While September 1st is the first day of meteorological fall, astronomical fall begins on September 22nd, so high temperatures in the 80s and 90s are still common in September. We missed out on a lot of heat this summer (especially compared to summers like 2012, 2011, and 2007), but we are making some ground late in the season. We are likely going to fall short of our yearly average number of 90°+ days (21 days) in 2013:

In the same week that we get summer heat, however, we’ll also get a true taste of fall. Low temperatures will likely be the 40s and 50s early Friday, Saturday, Sunday, Monday, and Tuesday morning. Here’s how forecast low temperatures match up against record low temperatures Friday through Sunday:

High and low temperatures will gladly return to near or above average into early next week. At this time, I don’t see any large temperature swings coming for the mid or latter part of next week.