🌊 US Weather Warriors MarineCast — Tuesday, July 21, 2026
Small Craft Advisories are up across every Delmarva marine zone — SW winds crank tonight with gusts to 30 kt and Atlantic seas building to 5–7 ft.
Today on the Water: SCAs blanket the coastal Atlantic, Delaware Bay, and the full Chesapeake, with most southern-zone advisories running through this afternoon and northern/bay zones extending into tonight or Wednesday. Gusty SSW winds ramp through the afternoon and hold into the overnight. Radar is quiet right now, but showers and thunderstorms move in this evening.
Atlantic Coastal Waters (Lewes → southern VA coast): SW 20–25 kt with gusts to 30 kt tonight, seas building to 5–7 ft on a 7-second S swell. Daytime hours are the least ugly window but still SCA-caliber. Thunderstorms roll in this evening.
Delaware Bay: SW 15–20 kt gusting 30 kt tonight, seas 2–4 ft with a short-period 5-second S swell stacking on a 2-second SW wind chop. Evening showers and storms likely.
Chesapeake Bay & Delmarva-facing Waters: SCA holds through this morning with channeling easing briefly midday before SSW winds refill at 15–20 kt gusting 30 kt this afternoon and evening. Waves running SW 3 ft at 3 seconds — short and stacked. Chance of showers and storms overnight.
Wind & Seas Outlook: Peak winds and peak seas both hit tonight (SW 20–25 kt gusting 30, Atlantic 5–7 ft). Conditions ease sharply by Thursday night into Friday as winds back to NE at 5–10 kt.
Marine Alerts:
- Small Craft Advisory — DE/VA Atlantic coastal waters, through 1 PM today
- Small Craft Advisory — NJ/DE Atlantic coast, through 5 PM today
- Small Craft Advisory — Delaware Bay, through 5 PM today
- Small Craft Advisory — Upper/Middle Chesapeake (MD), through 10:45 AM today
- Small Craft Advisory — Lower Chesapeake and Tidal Potomac (VA), through 1 PM today
Best Window to be Out: Mid-to-late morning on protected bay waters before the SSW afternoon surge — keep it short and stay near the ramp.
Worst Window: Tonight — 30-kt gusts, 5–7 ft Atlantic seas, and thunderstorms.
Bottom Line: Small boats stay in; larger, experienced crews can work sheltered bay waters this morning but need to be tied up before the afternoon SW winds fill in.
— US Weather Warriors #DelmarvaWeather #MarineWeather #BoatingWeather