FNUS71 KBOX 181312 FWSBOX Spot Forecast for Great Swamp...RI DEM National Weather Service Boston/Norton MA 912 AM EDT Mon May 18 2026 Forecast is based on ignition time of 1000 EDT on May 18. If conditions become unrepresentative, contact the National Weather Service. .DISCUSSION... Today near South Kingston: sunny and dry with SE winds that may occasionally gust close to 20 MPH this afternoon. Winds shift more S around 4 PM this afternoon. Minimum relative humidities are expected to be around 50 percent. Tonight, winds go light to calm from the SW/SSW. For Tuesday, winds pick up in the afternoon and gusts between 25-30 MPH are possible. Isolated thunderstorms are not out of the question in the afternoon as well, but the risk for scattered severe thunderstorms is higher Wednesday. Minimum relative humidities for Tuesday are expected around 50-55 percent once again, then to 45 percent on Wednesday. Winds for Wednesday afternoon will also likely be gusty to 25 MPH from the SW outside any thunderstorms that develop. Currently, the chance for showers and storms for Great Swamp on Wednesday is around 60 percent in the afternoon. High temperatures for both Tuesday and Wednesday are expected to climb into the 80s. .REST OF TODAY... Sky/weather.........Sunny. CWR.................1 percent. Max temperature.....Around 73. Min humidity........51 percent. Dewpoint............55. Max apparent temp...72. Surface winds (mph).Southeast winds 7 to 8 mph shifting to the south late in the afternoon. Wind (20 ft)........Southeast winds 7 to 8 mph. Mixing height.......1400 ft AGL. Transport winds.....Southeast 8 to 16 mph shifting to the south 9 to 13 mph late in the afternoon. Smoke dispersal.....Poor (8700 knot-ft) early in the morning increasing to fair (19600 knot-ft) in the afternoon. ADI.................13 to 29. CEILING (KFT).......25. TIME (EDT) 10A 11A 12P 1PM 2PM 3PM 4PM 5PM Sky (%).........18 15 10 13 20 19 13 10 Weather cov..... Weather type.... Tstm cov........ CWR.............0 0 0 0 0 0 0 0 Temp............70 72 72 72 72 72 72 71 Dewpoint........53 53 53 54 55 56 57 57 RH..............55 51 51 53 55 57 59 61 Heat index (F)..70 72 72 72 72 72 72 71 20 FT wind dir..E E E SE SE SE S S 20 FT wind spd..7 8 8 8 8 8 7 7 20 FT wind gust.15 16 15 15 14 15 15 16 Surface wnd dir.E E E SE SE SE S S Surface wnd spd.7 8 8 8 8 8 7 7 Surface wnd gst.15 16 15 15 14 15 15 16 Mix hgt (kft)...1.4 1.4 1.4 1.4 1.2 1.2 1.1 1.1 Transp wind dir.E E E E S S S SW Transp wind spd.16 16 13 10 8 9 12 13 ADI.............29 29 23 19 13 14 17 18 Vrate kt-ft/1K..19 20 16 13 9 10 11 12 Ventrate Cat....PR PR PR PR PR PR PR PR Ceiling (kft)...25 25 25 25 25 25 25 25 .TONIGHT... Sky/weather.........Partly cloudy then becoming mostly cloudy then becoming partly cloudy then becoming mostly cloudy. Patchy fog after midnight. CWR.................1 percent. Min temperature.....Around 58. Max humidity........96 percent. Dewpoint............57. Max apparent temp...68. Surface winds (mph).Southwest winds 5 to 6 mph. Wind (20 ft)........Southwest winds 5 to 6 mph. Mixing height.......400 ft AGL. Transport winds.....Southwest 10 to 13 mph. Smoke dispersal.....Poor (4300 knot-ft). ADI.................5 to 11. CEILING (KFT).......25 decreasing to 20 early in the evening, then increasing to 25 early decreasing to 20late in the evening decreasing to 15 increasing to 20 after midnight. TIME (EDT) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM Sky (%).........15 14 27 40 48 53 53 45 45 57 54 52 Weather cov..... PTY PTY PTY PTY PTY PTY Weather type.... FOG FOG FOG FOG FOG FOG Tstm cov........ CWR.............0 0 0 0 0 0 0 0 0 0 0 0 Temp............68 67 64 60 59 59 59 60 60 59 60 60 Dewpoint........58 57 57 57 57 57 57 57 58 58 58 58 RH..............70 70 78 90 93 93 93 90 93 96 93 93 Heat index (F)..68 67 64 60 59 59 59 60 60 59 60 60 20 FT wind dir..S S S SW SW SW SW SW SW SW SW SW 20 FT wind spd..6 5 5 5 5 5 5 5 5 5 5 6 20 FT wind gust.15 14 12 12 12 12 12 12 13 13 13 13 Surface wnd dir.S S S SW SW SW SW SW SW SW SW SW Surface wnd spd.6 5 5 5 5 5 5 5 5 5 5 6 Surface wnd gst.15 14 12 12 12 12 12 12 13 13 13 13 Mix hgt (kft)...0.7 0.5 0.4 0.4 0.4 0.5 0.5 0.5 0.5 0.4 0.4 0.4 Transp wind dir.SW SW SW SW SW SW SW W SW SW SW SW Transp wind spd.10 12 12 13 13 13 13 13 13 12 13 12 ADI.............10 11 5 6 8 8 8 8 8 8 8 11 Vrate kt-ft/1K..6 5 5 5 5 5 5 5 5 4 5 4 Ventrate Cat....PR PR PR PR PR PR PR PR PR PR PR PR Ceiling (kft)...25 20 25 20 20 15 20 20 20 20 20 20 .TUESDAY... Sky/weather.........Mostly sunny. Patchy fog early in the morning. CWR.................2 percent. Max temperature.....Around 81. Min humidity........53 percent. Dewpoint............60. Max apparent temp...82. Surface winds (mph).Southwest winds 6 to 13 mph. Wind (20 ft)........Southwest winds 6 to 13 mph. Mixing height.......1500 ft AGL. Transport winds.....Southwest 12 to 20 mph. Smoke dispersal.....Poor (4400 knot-ft) early in the morning increasing to fair (22100 knot-ft) in the afternoon. ADI.................11 to 30. CEILING (KFT).......14 decreasing to 11 early, then increasing to 14 late in the morning increasing to 20 early increasing to 22 decreasing to 18 late in the afternoon. TIME (EDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM Sky (%).........51 43 31 25 25 22 23 22 24 42 47 42 Weather cov.....PTY Weather type....FOG Tstm cov........ CWR.............0 0 0 0 0 0 0 0 0 0 0 0 Temp............60 64 67 71 75 78 79 81 81 80 78 76 Dewpoint........58 59 60 61 62 62 62 62 62 62 61 61 RH..............93 84 78 71 64 58 56 53 53 54 56 60 Heat index (F)..60 64 67 71 75 78 79 82 82 81 78 76 20 FT wind dir..SW SW SW SW SW SW SW SW SW SW SW SW 20 FT wind spd..6 6 6 7 8 10 12 12 13 13 13 12 20 FT wind gust.13 13 13 14 17 18 20 21 21 22 22 22 Surface wnd dir.SW SW SW SW SW SW SW SW SW SW SW SW Surface wnd spd.6 6 6 7 8 10 12 12 13 13 13 12 Surface wnd gst.13 13 13 14 17 18 20 21 21 22 22 22 Mix hgt (kft)...0.4 0.5 0.6 0.9 1.2 1.4 1.4 1.5 1.4 1.1 1.0 0.8 Transp wind dir.SW W W W W W W W SW SW SW SW Transp wind spd.12 12 13 15 17 17 17 17 18 18 20 18 ADI.............11 11 12 18 27 30 27 28 29 26 26 21 Vrate kt-ft/1K..4 5 7 12 18 20 21 22 22 18 18 13 Ventrate Cat....PR PR PR PR PR PR PR PR PR PRPR PR Ceiling (kft)...15 14 11 14 15 20 20 20 24 22 20 18 $$ Forecaster...Hrencecin Requested by...Waterman Type of request...PRESCRIBED .TAG 2613864.2/BOX .DELDT 05/18/26 .FormatterVersion 2.0.0 .EMAIL allan.waterman@dem.ri.gov