Accokeek, MD Weather

What Has Changed

Based on the latest observations and trends, including many personal weather station observations late this evening, have expanded the Frost Advisory and inserted a Freeze Warning. Most areas west of I-95 are now in a frost/freeze headline where the growing season remains active.

Key Messages

- 1) Another chilly night ahead with Frost Advisories in effect for portions of northern Virginia and central/northern Maryland.

- 2) Seasonable temperatures and dry conditions continue through much of next week.

Discussion

KEY MESSAGE 1...Another chilly night ahead with Frost Advisories in effect for portions of northern Virginia and central/northern Maryland.

High pressure will continue to meander over the area this evening before drifting southwest Sunday into Monday. As a result, expect a continuation of frost and freeze conditions during the overnight periods with seasonable temperatures during the daylight hours.

Tonight appears to be the coldest night of the next few given high pressure directly overhead. Hi-res CAM guidance continues to show persistence in regards to widespread frost and freeze conditions tonight, especially in locations west of I-95. Have expanded the Frost Advisory to include most of the rest of northern VA and to I-95 in MD, and inserted a Freeze Warning for northern MD down into portions of northern VA (Fauquier/Culpeper/W Loudoun).

These locations are also still in the growing season for 2026 while locations west of the Blue Ridge are no longer active. Locations east of the advisory (along and east of I-95) will also have a chance at some frost in the colder pockets, but should remain slightly warmer given the Chesapeake Bay influence. Confidence remains lower for an advisory expansion into central Virginia/southern MD due to higher dew points and potential cloud cover, as a remnant stratocumulus field continues to drift westward and possibly banking along the Blue Ridge overnight into early Sunday morning.

High pressure will gradually drift southwest toward the central Appalachians Sunday night into Monday morning. Low level flow will turn westerly allowing for less of a marine influence Sunday into Sunday night. This should set us up for one more good radiational cooling night (Sunday night) before temperatures warm under return flow early in the workweek. Sunday night will be more of a ridge- valley split type of night with cooler conditions in the valleys/cold pockets/locations along and east of I-95 compared to the ridge tops given the sharp surface inversion/decoupling.

Only minor changes have been made to the previous min temperature forecasts, which are near or below the coldest guidance which performs best in radiational cooling (MOS, NBM 10th percentile and Canadian Regional).

Aviation

Prevailing VFR conditions continue through early next week with broad high pressure nearby. A slight uptick in low level moisture will lead to an uptick in stratocumulus this evening east of the Blue Ridge along with the potential for some patchy river valley fog early Sunday/Monday mornings. Confidence overall is low in the coverage and timing of fog with a focus on Monday morning compared to Sunday morning given the lastest hi-res CAM guidance.

Winds will remain light and variable tonight before switching southeast to northeast SUnday as high pressure drifts overhead. Winds will change back to the northeast Monday with speeds both days less than 10kts.

VFR conditions are expected to continue through Thursday next week. Winds shift north to northwesterly Tuesday in the wake of a dry cold front, then shift east to southeasterly between Wednesday and Thursday. Cloud cover could begin to increase somewhat between Wednesday/Thursday as a frontal boundary approaches, but no precipitation is anticipated at this time.