September already? The ninth month brings us a welcome transition to autumn. Average high temperatures in Baltimore drop from 82 to 73 degrees. Overnight lows slide from 61 to 51. There's no record of snow here until October. The coldest reading was 35 degrees, on Sept. 25, 1963. The hottest was 101 degrees, on Sept. 7, 1881. This month brings the fourth anniversary of Tropical Storm Isabel, on the 18th; the fall equinox on the 23rd; and the full harvest moon on the 26th.