Temperatures here last week reached the 80s on a few days, a teasing reminder of summer. Eighty-degree days in October aren't exactly commonplace here, but they're not rare either. On average, the temperature reaches 80^oF on two days each October.

Ninety-degree days in October, however, are rare. In fact, I only found about five such days in the Wilmington and Philadelphia areas in the last 100 years, and those occurred early in the month. The latest in October for a 90^oF reading in Wilmington was October 7, back in 1941. In Philadelphia, the latest in the year to reach 90^oF was on this date, October 10, in 1939.

To get that warm in October, a couple things had to come together. First, the previous day and night were also very mild - the high was 86^oF the day before, and the overnight low was just 65^oF. The record-setting day itself was sunny with a strong southwest breeze, just the recipe for exceptional warmth. True to autumn form, however, a strong cold front came through that night - the high the next day was a more Octoberish 73^oF.