Cyndy Renoff asks, "When is the 'first frost' for Baltimore City? I'm just trying to plan when to bring my plants inside." That's hard to predict. The basil is safe in September, but can get zapped in mid-October. The earliest recorded subfreezing weather at BWI was Oct. 8 and 9, 2001, when morning lows hit 31 and 28 degrees. Across the state, the average first-frost days vary widely, from Sept. 10 in Oakland to Oct. 11 in Annapolis. Thanks to heat-island effects, Baltimore's is latest - Oct. 29.