Provincetown MA to Chatham MA to Nantucket MA out 20 NM Marine Forecast
| Tonight...Sw Winds 5 To 10 Kt. Seas 2 To 3 Ft. Wave Detail: E 3 Ft At 8 Seconds And Sw 1 Foot At 3 Seconds. |
| Thu...S Winds 5 To 10 Kt. Seas 2 To 3 Ft. Wave Detail: E 3 Ft At 8 Seconds And Sw 1 Foot At 4 Seconds. |
| Thu Night...Sw Winds 10 To 15 Kt. Gusts Up To 20 Kt After Midnight. Seas 2 To 3 Ft. Wave Detail: S 2 Ft At 3 Seconds And E 2 Ft At 7 Seconds. A Chance Of Showers After Midnight. |
| Fri...W Winds 10 To 15 Kt, Becoming N In The Afternoon. Gusts Up To 20 Kt. Seas 2 To 3 Ft. Wave Detail: Sw 2 Ft At 4 Seconds And E 2 Ft At 7 Seconds. A Chance Of Showers In The Morning. |
| Fri Night And Sat...Ne Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Wave Detail: N 4 Ft At 6 Seconds And Sw 1 Foot At 5 Seconds. |
| Sat Night...Se Winds 5 To 10 Kt. Seas 2 To 4 Ft. Wave Detail: E 3 Ft At 7 Seconds And Nw 1 Foot At 4 Seconds. |
| Sun And Sun Night...Se Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. A Chance Of Showers. |
| Mon And Mon Night...Ne Winds 15 To 20 Kt. Seas 3 To 5 Ft. A Chance Of Showers. Seas Are Reported As Significant Wave Height, Which Is The Average Of The Highest Third Of The Waves. Individual Wave Heights May Be More Than Twice The Significant Wave Height. |
| Area Forecast Discussion National Weather Service Boston/Norton MA 306pm EDT Wednesday September 16 2026 .WHAT HAS CHANGED... No significant changes to the forecast. .KEY MESSAGES... - Increased humidity and warmer temperatures continue tomorrow. - Scattered showers possible Thursday evening into Friday morning. - Rain chances return for the second half of the weekend. There remains uncertainty in the details such as coverage, timing, amounts. KEY MESSAGE 1...Increased humidity and warmer temperatures continue tomorrow. Warmer temperatures with increased humidity continue into tomorrow as an anomalous moisture plume and higher 925 mb temperatures advect into southern New England via SW flow. Looking ahead into tonight, the increased moisture and winds dropping off in the interior may favor the development of some patchy fog, especially in the CT Valley. With 925 mb temperatures reaching around 16-19C in the afternoon Thursday, high temperatures in the low 80s are a possibility, especially in the river valleys. These higher low level temperatures remain over the region overnight as well with high pressure affixed just to our south continuing SW flow; lows tonight will likely only drop into 60s as opposed to the areas of 50s and 40s we've seen the past few nights. PWATs (Precipitable Waters) up to 2.0" and dewpoints in the upper 60s will make it feel more humid, too. Despite the increased humidity, the region should remain dry for much of the day tomorrow. KEY MESSAGE 2...Scattered showers possible Thursday evening into Friday morning. Dry during the day Friday. A weak shortwave trough progresses eastward behind the plume of moisture, which will aid in the development of scattered showers across southern New England. As previously mentioned, latest guidance has shown PWATs (Precipitable Waters) reaching ans even exceeding 2.0" Thursday afternoon/evening. However, we are not anticipating widespread downpours as guidance continues to track the stronger forcing across northern parts of New England. Global models and a number of the CAMs (with the exception of the NAM) are in agreement that higher rainfall totals should generally remain to our north, and ensemble probabilities also favor this outcome. Totals across southern New England should primarily range between 0.1" to 0.3" based on the more northern track of the wave. The latest CAMs have still shown some elevated instability Thursday night, so a low chance of some isolated downpours cannot be completely ruled out. Totals could also increase slightly if the wave were to end up tracking a little further south, but the general consensus is that the greatest forcing will remain to our north and we could generally expect a few tenths of an inch. Following this system, drier air pushes back in with NW flow, which will aid in clearing skies through the day and bringing temperatures back to a more seasonable range. KEY MESSAGE 3... Rain chances return some time late Saturday night into Monday morning. There remains uncertainty in the details such as coverage, timing, amounts. A high pressure should move across northern New England Saturday, then over the North Atlantic Sunday. This should clear the path for a low pressure to move from the lower Great Lakes south of New England late some time late Saturday night into Monday. This will likely be our next period of rainfall. However, the timing is not yet finalized, especially with a high pressure over the ocean. Would not be surprised if a slower timing develops. There is also a question about how much rainfall we can expect across our region. High pressure over eastern Canada may nudge far enough south to pus the ultimate storm track far enough south where we could wind up dry Tuesday into Wednesday. Assuming this occurs, total rainfall amounts could be limited to a general 1-2 inches by Monday afternoon. Otherwise, with a nearly stationary front close to the south coast of New England could trigger some showers right into mid week. Marine Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through Thursday night...High confidence. High pressure continues along with SW winds at 10-15 kt into tomorrow. Gusts just under 20 kt are possible in the afternoon and evening hours. Chances for showers over the waters increase Thursday night, especially for northern parts of the eastern waters. Seas remain at 2-3 ft, though areas of the southern waters may approach 4 ft heading into Friday morning. Outlook /Friday through Monday/... Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Friday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Monday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine None. |
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