Marine Weather and Tide Forecast for Portsmouth, NH
April 18, 2025 2:39 AM EDT (06:39 UTC) Change Location
![]() | Sunrise 5:53 AM Sunset 7:30 PM Moonrise 12:38 AM Moonset 8:48 AM |
ANZ154 Coastal Waters From Cape Elizabeth, Me To Merrimack River, Ma Out 25 Nm- 1047 Pm Edt Thu Apr 17 2025
Overnight - W winds 5 to 10 kt. Seas around 2 ft. Wave detail: nw 2 ft at 3 seconds.
Fri - SW winds 5 to 10 kt, becoming S 15 to 20 kt with gusts up to 25 kt in the afternoon. Seas 2 to 3 ft. Wave detail: S 3 ft at 4 seconds.
Fri night - S winds 20 to 25 kt, becoming sw 15 to 20 kt after midnight. Seas 3 to 5 ft. Wave detail: S 5 ft at 6 seconds. A chance of showers after midnight.
Sat - SW winds 15 to 20 kt with gusts up to 25 kt. Seas 3 to 5 ft. Wave detail: S 5 ft at 6 seconds. A chance of showers in the morning.
Sat night - W winds 15 to 20 kt with gusts up to 25 kt. Seas 3 to 5 ft. Wave detail: S 5 ft at 8 seconds.
Sun - NW winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. Wave detail: S 4 ft at 9 seconds and W 3 ft at 4 seconds.
Sun night - NW winds 10 to 15 kt with gusts up to 25 kt. Seas 2 to 3 ft.
Mon - NW winds 5 to 10 kt, becoming S in the afternoon. Seas around 2 ft.
Mon night - S winds around 10 kt with gusts up to 20 kt. Seas around 2 ft. Showers likely after midnight.
Tue - S winds 10 to 15 kt with gusts up to 20 kt. Seas 2 to 4 ft. Showers likely, mainly in the morning.
Tue night - NW winds around 10 kt with gusts up to 20 kt. Seas 3 to 4 ft.
ANZ100 1047 Pm Edt Thu Apr 17 2025
Synopsis for stonington me to merrimack river ma out to 25 nm high pressure moves south of the waters tomorrow, with a warm front lifting across the waters this weekend warmer temperatures and increasing chances for showers are forecast. A cold front crosses the waters Saturday night into Sunday morning.
7 Day Forecast for Marine Location Near Portsmouth, NH

NEW! Add second zone forecast
Atlantic Heights Click for Map Thu -- 02:50 AM EDT 7.64 feet High Tide Thu -- 05:57 AM EDT Sunrise Thu -- 08:00 AM EDT Moonset Thu -- 09:04 AM EDT 0.48 feet Low Tide Thu -- 03:29 PM EDT 6.73 feet High Tide Thu -- 07:28 PM EDT Sunset Thu -- 09:09 PM EDT 1.37 feet Low Tide Tide / Current data from XTide NOT FOR NAVIGATION |   |
Atlantic Heights, Piscataqua River, New Hampshire, Tide feet
12 am |
4.8 |
1 am |
6.4 |
2 am |
7.4 |
3 am |
7.6 |
4 am |
7.1 |
5 am |
5.9 |
6 am |
4.1 |
7 am |
2.3 |
8 am |
1 |
9 am |
0.5 |
10 am |
0.8 |
11 am |
1.7 |
12 pm |
3.1 |
1 pm |
4.7 |
2 pm |
6 |
3 pm |
6.6 |
4 pm |
6.6 |
5 pm |
5.9 |
6 pm |
4.7 |
7 pm |
3.2 |
8 pm |
1.9 |
9 pm |
1.4 |
10 pm |
1.6 |
11 pm |
2.5 |
Portsmouth Harbor Entrance Click for Map Thu -- 12:32 AM EDT 1.17 knots Max Flood Thu -- 03:43 AM EDT -0.00 knots Slack Thu -- 05:57 AM EDT Sunrise Thu -- 07:07 AM EDT -1.79 knots Max Ebb Thu -- 08:00 AM EDT Moonset Thu -- 11:11 AM EDT 0.00 knots Slack Thu -- 01:01 PM EDT 0.93 knots Max Flood Thu -- 04:10 PM EDT -0.00 knots Slack Thu -- 07:25 PM EDT -1.44 knots Max Ebb Thu -- 07:28 PM EDT Sunset Thu -- 11:05 PM EDT 0.00 knots Slack Tide / Current data from XTide NOT FOR NAVIGATION |   |
Portsmouth Harbor Entrance, New Hampshire Current, knots
12 am |
1.1 |
1 am |
1.1 |
2 am |
0.7 |
3 am |
0.2 |
4 am |
-0.1 |
5 am |
-0.7 |
6 am |
-1.4 |
7 am |
-1.8 |
8 am |
-1.6 |
9 am |
-1.2 |
10 am |
-0.8 |
11 am |
-0.1 |
12 pm |
0.6 |
1 pm |
0.9 |
2 pm |
0.7 |
3 pm |
0.3 |
4 pm |
0 |
5 pm |
-0.3 |
6 pm |
-0.9 |
7 pm |
-1.4 |
8 pm |
-1.4 |
9 pm |
-1 |
10 pm |
-0.5 |
11 pm |
-0 |
Area Discussion for Gray/Portland, ME
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FXUS61 KGYX 180253 AFDGYX
Area Forecast Discussion National Weather Service Gray ME 1053 PM EDT Thu Apr 17 2025
SYNOPSIS
High pressure builds in from the southwest tonight into Friday.
A warm front lifts through the Northeast late Friday bringing chances for showers and much warmer conditions Saturday. A cold front crosses late Saturday with high pressure building in early next week.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
1045 PM Update...Little change to the going forecast. Clear skies and chilly temps continue to be the forecast overnight.
715 PM Update...Little change to the going forecast. A mostly clear and cold night is expected with diminishing winds for the balance of the evening hours.
Previously...
Mostly clear skies tonight as high pressure passes to the south. Low dewpoints in the teens today foreshadow cooling temps overnight, but elevated locations may remain lightly mixed overnight. Decoupling looks more likely in lower spots like valleys. Here, overnight lows may fall into the lower 20s to the upper teens.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/
Friday begins dry and sunny. Expect quick diurnal temperature recovery after sunrise from overnight lows. Temps climb for warmer day in the upper 50s to mid 60s. It will be less gusty, but drier across more of the forecast area with RH values falling into the 20 to 30 percent range. Winds become SW in return flow from high pressure passing offshore to the south.
High clouds begin to invade during the afternoon, lowering through late afternoon. Isolated to scattered showers develop in the mid to late afternoon west to east. Due to low level dry air, measurable precip should be light for the initial wave.
High res guidance following through the evening and overnight shows additional periods of rain and showers possible. These could add up to a wetting rain for much of the central forecast area, but uncertainty remains on positioning. A lot of this will be part of upstream convection exiting the northern Great Lakes and moving across southern Ontario and Quebec. With elevated instability, can't rule out some thunder overnight.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
1030 PM Evening update...01z NBM remains in line with the rest of the the latest guidance and therefore no significant changes have been made. Continued warm and cool interludes with no heavy precipitation events expected.
Previously...
Overview: The extended portion of the forecast will begin on a warm note with above average temperatures behind a warm frontal passage on Saturday. This will then be followed by a breezy and cooler day on Sunday behind a cold front. High pressure then builds in for Monday before shower chances from a weak disturbance increase on Tuesday. Mainly dry and seasonably warm conditions look to return for the middle of next week.
Impacts: No significant weather related impacts are expected through Saturday. West-northwesterly wind gusts could approach 35-45 mph on Sunday.
Forecast Details: Saturday will feature above average temperatures as we sit within the warm sector from closed low pressure that will be traveling across Quebec. Southwesterly WAA will help to boost h925 temperatures up to around +15C, which will allow highs to reach the lower to middle 70s in most locations with a few lower 80s possible in southern NH. The exception to the warmth will be along the Mid-Coast of ME where highs will likely only reach the 50s to near 60. Skies will be partly sunny but other than a few stray showers it should be a mostly dry day.
A strong cold front will cross on Saturday evening and night, bringing a few scattered showers and increasing westerly winds. Low temperatures will range from the 30s across the north/mtns to the 40s elsewhere. Deepening low pressure will track northeastward over southern Canada on Sunday as high pressure builds over the Great Lakes region. This will result in a strong pressure gradient over the forecast area, which combined with deep mixing will result in a breezy day. West-northwesterly wind gusts between 35-45 mph are likely with the potential for some stronger gusts. Blended in some NBM 75th percentile to account for this. Highs will also be about 20 degrees cooler, which combined with the winds will feel chilly compared to Saturday. Sunday night will be cold with lows falling into the 20s to lower 30s.
High pressure looks to build over the area on Monday, allowing for continued dry conditions and slightly warmer temperatures into the 50s and lower 60s. Shower chances then increase Monday night into Tuesday as a weak disturbance approaches from the west. High pressure then builds for the middle of next week.
AVIATION /03Z FRIDAY THROUGH TUESDAY/
Short Term...VFR with winds decreasing tonight. Winds increase again Friday morning, but not as gusty as today. SHRA chances increase late afternoon west to east, with additional showers overnight. LLWS is also possible overnight.
Long Term...VFR conditions will prevail through the period. A possible exception will be at KHIE where some restrictions are possible on Saturday and again on Sunday due to -SHRA and lower ceilings. West-northwesterly winds could approach 35 kts on Sunday.
MARINE
Short Term...High pressure passes south of the waters tonight and tomorrow. Return flow brings a S wind shift over the waters with increasing winds. A surface inversion may keep these winds below SCA criteria, but gusts 25 to 30 kt may be attainable once rain moves overhead.
Long Term...Southwesterly wind gusts between 25-30 kts are possible on Saturday with seas of 4-7 ft over the outer waters.
Winds will become west-northwesterly behind a cold front on Saturday night and Sunday with a few gusts up to 35 kts possible. High pressure will bring lighter winds and smaller seas early next week.
GYX WATCHES/WARNINGS/ADVISORIES
ME...None.
NH...None.
MARINE...None.
Area Forecast Discussion National Weather Service Gray ME 1053 PM EDT Thu Apr 17 2025
SYNOPSIS
High pressure builds in from the southwest tonight into Friday.
A warm front lifts through the Northeast late Friday bringing chances for showers and much warmer conditions Saturday. A cold front crosses late Saturday with high pressure building in early next week.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
1045 PM Update...Little change to the going forecast. Clear skies and chilly temps continue to be the forecast overnight.
715 PM Update...Little change to the going forecast. A mostly clear and cold night is expected with diminishing winds for the balance of the evening hours.
Previously...
Mostly clear skies tonight as high pressure passes to the south. Low dewpoints in the teens today foreshadow cooling temps overnight, but elevated locations may remain lightly mixed overnight. Decoupling looks more likely in lower spots like valleys. Here, overnight lows may fall into the lower 20s to the upper teens.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/
Friday begins dry and sunny. Expect quick diurnal temperature recovery after sunrise from overnight lows. Temps climb for warmer day in the upper 50s to mid 60s. It will be less gusty, but drier across more of the forecast area with RH values falling into the 20 to 30 percent range. Winds become SW in return flow from high pressure passing offshore to the south.
High clouds begin to invade during the afternoon, lowering through late afternoon. Isolated to scattered showers develop in the mid to late afternoon west to east. Due to low level dry air, measurable precip should be light for the initial wave.
High res guidance following through the evening and overnight shows additional periods of rain and showers possible. These could add up to a wetting rain for much of the central forecast area, but uncertainty remains on positioning. A lot of this will be part of upstream convection exiting the northern Great Lakes and moving across southern Ontario and Quebec. With elevated instability, can't rule out some thunder overnight.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
1030 PM Evening update...01z NBM remains in line with the rest of the the latest guidance and therefore no significant changes have been made. Continued warm and cool interludes with no heavy precipitation events expected.
Previously...
Overview: The extended portion of the forecast will begin on a warm note with above average temperatures behind a warm frontal passage on Saturday. This will then be followed by a breezy and cooler day on Sunday behind a cold front. High pressure then builds in for Monday before shower chances from a weak disturbance increase on Tuesday. Mainly dry and seasonably warm conditions look to return for the middle of next week.
Impacts: No significant weather related impacts are expected through Saturday. West-northwesterly wind gusts could approach 35-45 mph on Sunday.
Forecast Details: Saturday will feature above average temperatures as we sit within the warm sector from closed low pressure that will be traveling across Quebec. Southwesterly WAA will help to boost h925 temperatures up to around +15C, which will allow highs to reach the lower to middle 70s in most locations with a few lower 80s possible in southern NH. The exception to the warmth will be along the Mid-Coast of ME where highs will likely only reach the 50s to near 60. Skies will be partly sunny but other than a few stray showers it should be a mostly dry day.
A strong cold front will cross on Saturday evening and night, bringing a few scattered showers and increasing westerly winds. Low temperatures will range from the 30s across the north/mtns to the 40s elsewhere. Deepening low pressure will track northeastward over southern Canada on Sunday as high pressure builds over the Great Lakes region. This will result in a strong pressure gradient over the forecast area, which combined with deep mixing will result in a breezy day. West-northwesterly wind gusts between 35-45 mph are likely with the potential for some stronger gusts. Blended in some NBM 75th percentile to account for this. Highs will also be about 20 degrees cooler, which combined with the winds will feel chilly compared to Saturday. Sunday night will be cold with lows falling into the 20s to lower 30s.
High pressure looks to build over the area on Monday, allowing for continued dry conditions and slightly warmer temperatures into the 50s and lower 60s. Shower chances then increase Monday night into Tuesday as a weak disturbance approaches from the west. High pressure then builds for the middle of next week.
AVIATION /03Z FRIDAY THROUGH TUESDAY/
Short Term...VFR with winds decreasing tonight. Winds increase again Friday morning, but not as gusty as today. SHRA chances increase late afternoon west to east, with additional showers overnight. LLWS is also possible overnight.
Long Term...VFR conditions will prevail through the period. A possible exception will be at KHIE where some restrictions are possible on Saturday and again on Sunday due to -SHRA and lower ceilings. West-northwesterly winds could approach 35 kts on Sunday.
MARINE
Short Term...High pressure passes south of the waters tonight and tomorrow. Return flow brings a S wind shift over the waters with increasing winds. A surface inversion may keep these winds below SCA criteria, but gusts 25 to 30 kt may be attainable once rain moves overhead.
Long Term...Southwesterly wind gusts between 25-30 kts are possible on Saturday with seas of 4-7 ft over the outer waters.
Winds will become west-northwesterly behind a cold front on Saturday night and Sunday with a few gusts up to 35 kts possible. High pressure will bring lighter winds and smaller seas early next week.
GYX WATCHES/WARNINGS/ADVISORIES
ME...None.
NH...None.
MARINE...None.
Stations | Dist | Age | Wind | Air | Water | Waves | inHg | DewPt |
SEIM1 | 1 mi | 51 min | 42°F | 30.19 | ||||
BGXN3 - Great Bay Reserve, NH | 3 mi | 114 min | WNW 4.1 | 39°F | 27°F | |||
IOSN3 - Isle of Shoals, NH | 11 mi | 39 min | WNW 8G | 45°F | 30.16 | 2°F | ||
44073 | 13 mi | 194 min | W 9.7G | 47°F | 41°F | |||
44030 - Buoy B0102 - Western Maine Shelf | 19 mi | 95 min | WNW 5.8G | 42°F | 41°F | 1 ft | 30.12 | |
WEXM1 - Wells Reserve, ME | 21 mi | 99 min | WSW 1.9 | 40°F | 12°F | |||
44098 - Jeffrey's Ledge, NH (160) | 37 mi | 43 min | 42°F | 2 ft | ||||
44029 - Buoy A0102 - Mass. Bay/Stellwagen | 40 mi | 95 min | SW 1.9G | 44°F | 1 ft | 30.15 | ||
44007 - PORTLAND 12 NM Southeast of Portland,ME | 45 mi | 39 min | WSW 3.9G | 41°F | 41°F | 30.16 | 30°F | |
CASM1 - 8418150 - Portland, ME | 49 mi | 51 min | SW 7G | 41°F | 30.14 |
Wind History for No Ports station near this location
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Link to 1 hour of 5 minute data for KPSM
Terminal Aerodrome Forecast (TAF) for KPSM
Wind History Graph: PSM
(wind in knots)GEOS Local Image of Northeast
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Portland, ME,

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