The Casco Bay Report
Wind, water and sky between Portland Head Light and Bailey Island — read off the instruments each hour and set down in plain language.
Monday, August 17·Today’s reckoningCompiled 5:04 PM EDT
The State of the Bay
Taken at the hour from the harbour sensors, the offshore buoy and the forecast grid.
65°F
mainly clear
feels 63°
The air
Dew point62°
Humidity92%
Cloud cover43%
Visibility25.1 mi
Barometer1010.8 mb
steady
Sun strength0.3
low
Fog84 of 100
likely — warm air over cold water
The wind
out of the south-southeast
Force 4 · Moderate breeze
SSE · 168°
long fetch. Onshore off the Gulf. Builds steady sea and pushes swell into the outer islands.
59°F
water — cold
The sea
Significant height2.6 ft
slight
Dominant period5 s
Ground swell2.3 ft
at 5 seconds
Current at the entrance0.5 kt
ebbing, setting SE
Wind is running against the tide. The seas will stand up short and steep — worse than the height alone suggests, and worst at the harbour entrance.
Cold-shock response is real here. Wetsuit recommended; survival time 1–6 hours.
The Tide at Portland
AVERAGE RANGEPredicted from NOAA station 8418150 and checked against the measured water level. Heights are feet above mean lower low water.
9.0ft
and ebbing
-1.86 ft/hr
| Tide | Time | Height |
|---|---|---|
| Low | 9:34 PM | 0.3 |
| HighTue | 3:47 AM | 9.1 |
| LowTue | 9:49 AM | 0.7 |
| HighTue | 4:07 PM | 9.6 |
| LowTue | 10:27 PM | 0.7 |
| HighWed | 4:40 AM | 8.5 |
Next low9:34 PM
4h 30m from now
Range today9.7 ft
107% of the 9.1 ft mean
Against prediction+0.83 ft
Water is running high — wind setup
The Sun and the Moon
13h 54m of daylight, losing 3 min a dayComputed for 43°42′ N, 70°09′ W — the middle of the bay, between Long Island and Chebeague.
The sun
First light civil dawn | 5:16 AM |
Sunrise golden until 6:26 AM | 5:47 AM |
Highest 59.6° above the horizon | 12:44 PM |
Golden hour the good light | 7:01 PM |
Sunset | 7:41 PM |
Last light full dark at 9:30 PM | 8:11 PM |
The sun stands 27.1° up, bearing 262° — w of you.
The moon
Waxing Crescent
26.8% lit · 5.1 days old
Rises11:26 AM
Sets9:40 PM
Next fullAug 28
Next newSep 10
Feeding periods49
The old solunar reckoning: fish move hardest when the moon is on the meridian — overhead or underfoot — and again at its rising and setting. Lay a major period over a running tide and that is your hour.
| Period | From | To |
|---|---|---|
| Moon underfootmajor | 3:20 AM | 5:20 AM |
| Moonriseminor | 10:56 AM | 11:56 AM |
| Moon overheadmajor | 3:35 PM | 5:35 PM |
| Moonsetminor | 9:10 PM | 10:10 PM |
Notices to Mariners
What would catch you out today, and what is worth going out for.
Fog likely
Elevated fog risk from 6:00 PM to 2:00 PM tomorrow. Warm air over cold water — the classic Casco Bay setup. Carry radar and sound your horn.
Wind against tide
Around 6:00 PM the breeze opposes the current. Seas will stand up short and steep — worse than the 2.5 ft height suggests, especially at the harbor entrance.
Wind peaks
SSE 13 kt, gusts 15 around 6:00 PM.
Water 59°F — cold
Cold-shock response is real here. Wetsuit recommended; survival time 1–6 hours.
Evening golden hour
Starts 7:01 PM, sunset 7:41 PM, civil dusk 8:11 PM. Day length is shrinking by 3 min a day right now.
Best window 11:00 AM tomorrow
NNE 7 kt, 1.4 ft seas, flood tide. Best combination of breeze and sea state in the next 24 hours.
Hour by Hour
The next day and night, read off the forecast grid and joined to the tide and the current at the harbour entrance.
| Hour | Weather | Air | Wind | Gust | Sea | Per. | Tide | Set | Curr. | Rain | Vis. | Fog |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| now | Mainly clear | 65° | SSE 13 | 15 | 2.6 | 4s | 8.3 | ebb | 0.5 | 1% | 25 | 81 |
| 6 PM | Partly cloudy | 65° | SSE 13 | 15 | 2.5 | 4s | 6.2 | ebb | 0.9 | 1% | 25 | 91 |
| 7 PM | Overcast | 65° | SSE 13 | 16 | 2.4 | 5s | 3.7 | ebb | 1.0 | 1% | 25 | 91 |
| 8 PM | Clear sky | 65° | S 10 | 14 | 2.3 | 5s | 1.6 | ebb | 0.9 | 1% | 25 | 92 |
| 9 PM | Clear sky | 65° | S 9 | 10 | 2.2 | 5s | 0.5 | low | 0.6 | 2% | 25 | 92 |
| 10 PM | Clear sky | 65° | SSE 5 | 8 | 2.0 | 5s | 0.4 | low | 0.3 | 1% | 25 | 100 |
| 11 PM | Clear sky | 64° | SE 6 | 5 | 1.9 | 5s | 1.4 | flood | 0.1 | 1% | 25 | 100 |
| 12 AMTue | Clear sky | 64° | SE 6 | 5 | 1.8 | 5s | 3.3 | flood | 0.4 | 1% | 25 | 100 |
| 1 AM | Overcast | 64° | E 5 | 6 | 1.7 | 5s | 5.6 | flood | 0.6 | 1% | 25 | 100 |
| 2 AM | Overcast | 64° | ENE 5 | 6 | 1.6 | 5s | 7.6 | flood | 0.5 | 3% | 25 | 100 |
| 3 AM | Overcast | 64° | E 6 | 6 | 1.5 | 5s | 8.8 | flood | 0.3 | 5% | 25 | 100 |
| 4 AM | Partly cloudy | 64° | ESE 6 | 8 | 1.5 | 5s | 9.1 | high | 0.1 | 3% | 25 | 100 |
| 5 AM | Mainly clear | 64° | E 7 | 7 | 1.4 | 5s | 8.4 | ebb | 0.3 | 3% | 2.4 | 100 |
| 6 AM | Fog | 64° | NE 8 | 7 | 1.4 | 5s | 6.7 | ebb | 0.7 | 2% | 0.2 | 96 |
| 7 AM | Fog | 64° | NE 8 | 9 | 1.4 | 5s | 4.5 | ebb | 0.9 | 4% | 0.4 | 96 |
| 8 AM | Fog | 64° | NNE 6 | 8 | 1.4 | 5s | 2.4 | ebb | 0.9 | 3% | 0.8 | 96 |
| 9 AM | Overcast | 64° | N 6 | 10 | 1.4 | 5s | 1.1 | ebb | 0.6 | 1% | 25 | 80 |
| 10 AM | Overcast | 65° | NNE 7 | 11 | 1.4 | 5s | 0.8 | low | 0.3 | 2% | 25 | 80 |
| 11 AM | Overcast | 65° | NNE 7 | 11 | 1.4 | 6s | 1.5 | flood | 0.0 | 3% | 25 | 74 |
| 12 PM | Overcast | 65° | NNE 6 | 10 | 1.4 | 6s | 3.1 | flood | 0.3 | 1% | 25 | 63 |
| 1 PM | Overcast | 65° | NNE 5 | 9 | 1.4 | 6s | 5.3 | flood | 0.5 | 3% | 25 | 78 |
| 2 PM | Overcast | 65° | NNE 3 | 9 | 1.5 | 6s | 7.5 | flood | 0.5 | 7% | 25 | 66 |
| 3 PM | Overcast | 65° | NW 2 | 8 | 1.6 | 6s | 9.0 | flood | 0.3 | 4% | 25 | 38 |
| 4 PM | Overcast | 66° | NNE 4 | 9 | 1.6 | 6s | 9.6 | high | 0.1 | 4% | 26 | 52 |
| 5 PM | Overcast | 65° | ENE 3 | 9 | 1.6 | 6s | 9.2 | ebb | 0.2 | 3% | 25 | 62 |
Sea in feet, period in seconds, tide in feet above mean lower low water, current in knots at the harbour entrance, visibility in miles, fog on a scale of one hundred.
From the Weather Service
The official word, printed as issued. Where this page disagrees with the bulletin, believe the bulletin.
Coastal Waters Forecast
National Weather Service · Gray, Maine
Zone ANZ153 — Casco Bay
National Weather Service · Gray, Maine
Zone ANZ153 — Casco Bay
Issued 2:36 PM EDT
.SYNOPSIS... High pressure slides south into midweek, with a cold front approaching the waters Wednesday evening. High pressure then returns for the end of the week.
.This Afternoon... S winds 10 to 15 kt. Seas 2 to 3 ft.
.Tonight... S winds 5 to 10 kt, becoming E after midnight. Seas 2 to 3 ft. Patchy fog in the evening, then areas of fog after midnight. Vsby 1 NM or less.
.Tue... NE winds around 5 kt. Seas around 2 ft. Areas of fog in the morning with vsby 1 NM or less.
.Tue Night... E winds around 5 kt, becoming NW after midnight. Seas 2 to 3 ft. Patchy fog. Vsby 1 NM or less.
.Wed... SW winds around 5 kt, becoming S in the afternoon. Seas 2 to 4 ft.
.Wed Night... S winds 5 to 10 kt, becoming W after midnight. Seas 2 to 3 ft.
.Thu... NW winds around 5 kt, becoming S in the afternoon. Seas 2 to 3 ft.
.Thu Night... SW winds around 5 kt, becoming N after midnight. Seas around 2 ft.
Ashore
This Afternoon
Mostly cloudy, with a high near 66. South wind around 15 mph.
Tonight
Areas of fog after 8pm. Mostly cloudy, with a low around 63. Southeast wind 0 to 15 mph.
Tuesday
Areas of fog before 11am, then a slight chance of rain showers between 1pm and 2pm. Mostly cloudy, with a high near 70. Northeast wind around 5 mph. Chance of precipitation is 20%.
Tuesday Night
Patchy fog between 11pm and 4am. Mostly cloudy, with a low around 63. Northwest wind 0 to 5 mph.
Wednesday
Mostly sunny, with a high near 72. Southwest wind 0 to 15 mph.
Wednesday Night
Partly cloudy, with a low around 64.
The Week Ahead
Wave heights run out past two and a half days — beyond that the marine model has nothing honest to say, and the column is left blank.
| Day | Weather | High | Low | Wind | Gust | Sea | Rain | Moon | High water |
|---|---|---|---|---|---|---|---|---|---|
| TodayAug 17 | Overcast | 66° | 64° | S 16 | 26 | 3.0 | 17% | Waxing Crescent27% | 2:55 AM · 3:19 PM |
| TueAug 18 | Fog | 66° | 64° | NNE 8 | 12 | 2.1 | 8% | Waxing Crescent36% | 3:47 AM · 4:07 PM |
| WedAug 19 | Overcast | 86° | 64° | SSW 10 | 14 | 2.2 | 8% | Waxing Crescent46% | 4:40 AM · 4:57 PM |
| ThuAug 20 | Heavy drizzle | 77° | 62° | NE 7 | 9 | 1.7 | 12% | Waxing Gibbous55% | 5:36 AM · 5:51 PM |
| FriAug 21 | Overcast | 79° | 60° | SE 9 | 10 | — | 4% | Waxing Gibbous65% | 6:35 AM · 6:48 PM |
| SatAug 22 | Overcast | 79° | 61° | S 8 | 13 | — | 17% | Waxing Gibbous74% | 7:36 AM · 7:47 PM |
| SunAug 23 | Heavy drizzle | 79° | 63° | SSE 9 | 11 | — | 41% | Waxing Gibbous81% | 8:35 AM · 8:43 PM |
From the Buoys and Gauges
Measured, not modelled. These are the actual instruments in the water, with the age of each reading.
| Station | Distance | Wind | Sea | Per. | Swell | Water | Air | Age |
|---|---|---|---|---|---|---|---|---|
| Portland Harbour station 8418150, on the waterfront | — | S 12 | — | — | — | 59.4° | 68.0° | 10m |
| Portland Lightship Buoy buoy 44007 — 12 nm southeast of portland — the bay's reference buoy | 10.5 nm | S 8 | 2.6 | 5s | 2.3 SSE | 60.4° | 64.2° | 24m |
| Western Maine Shelf buoy 44030 — wind and air temperature on the western shelf | 33.5 nm | S 10 | 2.6 | 5s | — | 66.2° | 67.8° | 1h 34m |
| Jeffreys Ledge buoy 44098 — offshore to the south — shows swell arriving from the gulf | 54.2 nm | — | 2.6 | 4s | 0.3 ESE | 67.6° | 68.0° | 34m |
| Jonesport, Maine buoy 44027 — down east — early warning for weather tracking southwest | 128 nm | S 12 | 3.0 | 6s | 1.6 SSW | 55.8° | —° | 34m |
Freshwater into the bay
Presumpscot579 cfs
enters at Falmouth
Royal28 cfs
enters at Yarmouth
Androscoggin2,090 cfs
enters at Merrymeeting Bay
After rain the plume freshens and clouds the top few feet near the river mouths, and carries stormwater down with it for a day or two.
Air and sky
Air quality54
moderate
GeomagneticKp 2.7
no northern lights tonight
Casco Bay lies near 53° magnetic latitude. It takes Kp 6 or better before the lights clear the horizon, and you want to be off away from Portland’s glow — Chebeague, Cliff, or the north shore of Bailey.
Last reading 11:00 AM EDT