Delaware's First Frost: What You Need to Know

Delaware is preparing for its first frost of the year. The National Weather Service has issued a frost advisory for most of the state, excluding the beaches in Sussex. This advisory is in effect from 2 a.m. to 9 a.m. on October 25.

Understanding Frost

Frost forms when temperatures drop to 32 degrees or lower. This can be harmful to sensitive outdoor plants. If left uncovered, these plants may not survive the cold.

• 38-42 degrees: Frost can develop.
• 33-37 degrees: Patchy frost is possible.
• 32 degrees or below: Widespread frost is likely.

Upcoming Weather Forecast

The forecast for Delaware looks chilly:

• Lows: 30s and 40s in Wilmington, Dover, and Georgetown.
• Highs: Mid-50s to low 60s.
• Duration: Cold weather is expected through the weekend and into next week.

Factors Contributing to Frost Formation

Several factors contribute to frost formation:

• Clear skies: Allow heat to escape into the atmosphere.
• Light winds: Create a thin layer of super-cooled air near the ground.
• Cool temperatures with moisture: Promote ice crystal development.
• Local topography: Cold air settles in valleys, making frost more likely.

Average First Frost Dates

The first frost in Delaware usually occurs in late October or early November. However, the exact date can vary depending on the location:

• Bear: Average first frost on October 28.
• Hockessin: Average first frost on October 19.

Historically Cold Octobers

Delaware has seen some notably cold Octobers in the past:

• 1907: Coldest October on record with an average temperature of 51 degrees.
• 1895, 1988, 1925: Other chilly Octobers with average temperatures ranging from 51 to 52 degrees.