Just when you thought it was safe to go back in the water — it is.
The National Oceanic and Atmospheric Administration has created a website that forecasts the location of sea nettles throughout the Chesapeake and its tributaries.
NOAA colors the Bay map according to a sliding population scale, using bright red for heavily infested and cool blue for jelly-free swim zones.
To predict nettle nests in the water, scientists relied on their knowledge of environmental factors. Using satellite imagery and Bay salinity estimates, NOAA can tell you which areas of the Bay have a higher probability of nettle life. The stinging creatures prefer warm conditions or middle-Bay tributaries.
The predictions are verified by Alliance for the Chesapeake Bay volunteers and scientists who take to the waters in search of the nettles.
Swimmers and boaters can find daily and three-day forecasts at http://chesapeakebay.noaa.gov/forecasting-sea-nettles.