Coastal Jefferson Parish- Including the city of Grand Isle 1232 PM CDT Sun Jul 20 2025 .THIS AFTERNOON...Sunny with a slight chance of showers and thunderstorms. Near steady temperature in the upper 80s. South winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 105. .TONIGHT...Mostly clear. Humid with lows in the upper 70s. Southwest winds 5 to 10 mph. .MONDAY...Sunny with highs around 90. West winds around 5 mph, becoming south around 5 mph in the afternoon. Heat index values up to 105. .MONDAY NIGHT...Mostly clear. Humid with lows in the upper 70s. Southwest winds around 5 mph. .TUESDAY...Sunny with a slight chance of showers and thunderstorms. Humid with highs in the lower 90s. West winds around 5 mph. Chance of rain 20 percent. Heat index values up to 106. .TUESDAY NIGHT...Mostly clear. A slight chance of showers and thunderstorms after midnight. Lows in the upper 70s. Chance of rain 20 percent. .WEDNESDAY...Mostly sunny. A chance of showers and thunderstorms in the morning, then showers and thunderstorms likely in the afternoon. Highs in the lower 90s. Chance of rain 60 percent. Heat index values up to 105. .WEDNESDAY NIGHT...A chance of showers and thunderstorms in the evening, then showers and thunderstorms likely after midnight. Lows in the mid 70s. Chance of rain 70 percent. .THURSDAY...Showers, thunderstorms. Near steady temperature in the lower 80s. Chance of rain 90 percent. .THURSDAY NIGHT...A chance of thunderstorms. A chance of showers in the evening, then showers likely after midnight. Near steady temperature in the lower 80s. Chance of rain 70 percent. .FRIDAY...Showers, thunderstorms. Near steady temperature in the lower 80s. Chance of rain 90 percent. .FRIDAY NIGHT...Mostly cloudy in the evening, then becoming partly cloudy. A chance of showers and thunderstorms. Near steady temperature in the lower 80s. Chance of rain 50 percent. .SATURDAY...Showers likely with a chance of thunderstorms in the morning, then showers and thunderstorms in the afternoon. Highs in the upper 80s. Chance of rain 80 percent.