A killing frost in August? It can happen, and it did happen, 25 years ago yesterday. The overnight low in Oakland, in far Western Maryland, was 28 degrees, and garden veggies turned to mush. The day's low at BWI Airport set a record at 49. Three inches of snow drew skiers to Killington, Vt. Record lows were set across the Midwest and Northeast. Scientists blamed stratospheric debris from Mexico's El Chichon volcano. It erupted in April 1982, and its dust circled the globe, dimming sunshine for a year.