Maryland weather: Season’s first frost forecast early Saturday in parts of the Baltimore region

The season’s first frost is forecast early Saturday morning in the northern and western Baltimore suburbs.

Temperatures are forecast to drop into the lower 30s in Howard, Carroll, northern Baltimore and northern Harford counties, a sign the growing season is coming to an end. Frost can damage or kill sensitive crops and outdoor plants.

Overnight lows are forecast in the mid- to upper 30s around Baltimore and along the Interstate 95 corridor. The urban heat island effect and the influence of Chesapeake Bay waters that are still relatively warm help delay the arrival of winter in those areas.

The timing is normal for typically cooler areas at slightly higher elevations such as Westminster and Frederick. Temperatures normally drop below freezing by late October in those areas, according to the University of Maryland Extension.

The season’s first freeze arrives by Oct. 28, on average, at Baltimore-Washington International Thurgood Marshall Airport. In Baltimore City, it often doesn’t come until mid-November.

A freeze appears imminent farther west. A freeze warning is in effect overnight in Washington and Allegany counties. Temperatures have already dropped below freezing this season in Garrett County.