Is the sea rising?
Yes: about since 1912.
And it's speeding up. Over the last 30 years it rose about 1.9× faster than the century average.
- NOAA has measured the tide in Portland every month since 1912. That long record makes this one of our surest answers.
- Every high tide and every storm now starts from higher water, which is a big reason beaches and dunes erode.
- The 2024 record storm beat the Blizzard of '78 by about 5 inches, and roughly 74% of that was just the higher sea.
- At 12 ft, the National Weather Service's minor flood level, low wharves and side streets near Portland Pier start to flood. Before 1950 that happened less than one day a year; over the last ten years it averaged about 7 days a year.
Sea level at Portland, 1912 to today
How to read it: each dot is one year's average, measured as how much higher it was than in 1912. The orange line is the long-term trend.
Flooding is becoming routine
How to read it: each bar is a year: the days the water reached 12 ft, the level at which low wharves near Portland Pier start to flood. Orange steps are decade averages.
Same storm, higher sea: 1978 vs 2024
How to read it: the 2024 record beat the Blizzard of '78 by this much. Blue is how much the sea itself rose in between.
How we measured it
Yearly averages of NOAA monthly mean sea level at Portland (station 8418150), with a straight-line trend: 1.97 ± 0.34 mm per year (95% range, widened because one year is related to the next). Last 30 years: 3.7 ± 1.4 mm per year.
How high can the water get?
The record is , in 2024.
That's above an ordinary high tide. Tap the buttons to see how high different events reach.
- Surprise: this year's highest water (Jun 16, 2026) wasn't a storm. It was mostly a king tide, when the Moon and Sun line up, plus a few inches of extra water.
- The biggest storm surge this year was of extra water, on Feb 23, 2026.
Highest water each year since 1912
How to read it: each dot is one year's highest water, adjusted to today's sea level. Big orange dots reached the "1-in-10-year" level.
Storm surge over the past year
How to read it: how far above or below the tide tables the water ran (daily average). Orange bands are storms at Camp Ellis.
How we measured it
Generalized extreme value fit to the highest water of each year at Portland, shifted to today's sea level. "1-in-100-year" means a 1% chance in any year, not once a century. 100-year level 4.37 m above MLLW (likely range 4.22–4.53). Surge = measured water minus NOAA's predicted tide.
Was it a warm year or a cold one?
The sea ran a little warm: about above normal.
Off Portland, the warmest months compared with normal were October and June. The Gulf of Maine has warmed about per decade since 1990.
- 🏊 30 swim days at Camp Ellis (water at least ), from Jun 13 to Sep 05.
- 🦞 108 hours warm enough to stress lobsters (above ).
- In summer the sea forms layers, warm on top and cold below, like oil on vinegar. Pick a month above to see it.
Sea temperature vs normal
How to read it: the grey band is a normal range for each date. Above the band means unusually warm.
The Gulf of Maine is warming
How to read it: one stripe per year at NOAA buoy 44007: blue cooler and red warmer than the 1991–2020 average. Gaps are years with too little data.
Air temperature vs normal
How to read it: each bar is a week: red was warmer than normal, blue colder.
Layers in the sea at Camp Ellis
How to read it: the shaded area is how much warmer the top is than the bottom. Big gap = layered; near zero = mixed.
How we measured it
Normal = 1991–2020 average for each date at NOAA buoy 44007 (±5 days, smoothed); band = 10th–90th percentile. Marine heatwave test: Hobday et al. (2016). Layers from the three sensors on the Camp Ellis mooring.
Where does the sand go?
North, away from Camp Ellis.
Waves at Camp Ellis roll in from the east, east-southeast and southeast, a little south of straight on for this beach, so they push sand north along the shore like a slow conveyor belt. The jetty blocks new sand from the Saco River, so Camp Ellis loses sand while beaches to the north gain it.
- This matches decades of geology in Saco Bay: Pine Point has grown while Camp Ellis has eroded.
- Storms do most of the work: they were only 7% of the hours but moved about 52% of the sand.
- The busiest single storm (Sep 24, 2026) moved about 16% of the whole year's sand by itself.
- Out on the seabed near the buoy, the sand only moves about 15% of the time, mostly in winter storms.
Camp Ellis through time
Why the sand matters here: the jetty cut the beach off from the river's sand, and waves keep carrying sand north.
- 1867The Army Corps of Engineers builds a jetty at the mouth of the Saco River to keep the channel open for ships. It also blocks the river's sand from reaching Camp Ellis beach.
- 1908Camp Ellis's shoreline sits about 400 feet farther out to sea than it would a century later.
- 1912The Corps adds a spur to the jetty. Engineers at the time thought sand moved north to south; later research found it moves the other way.
- 1953The Surf Street seawall (about 700 feet long) is built to hold back the sea.
- 1955A Corps study estimates the area lost about 5.9 million cubic metres of sand since 1869, but concludes the jetty wasn't the cause.
- 1978The Blizzard of '78 sets Portland's water-level record. Photos show waves bouncing off the jetty into Camp Ellis.
- 1983Maine's Sand Dune Rules ban new seawalls and limit rebuilding of houses badly damaged by storms.
- 2007The Patriots' Day storm (April) destroys another Camp Ellis house.
- 2022–23$45 million is announced (2022) for a 750-foot spur off the jetty to protect Camp Ellis; the Army Corps finalizes the plan in 2023.
- Since 1950sMeanwhile, sand drifting north has built up Pine Point, enough to support about 50 more homes over 50 years.
Sources: UMaine Sea Grant, Maine Monitor, Kelley et al. 2006.
Where the wave energy comes from
How to read it: the yellow line is the beach. Dark petals show where waves come from; petals in the blue half push sand north.
Sand pushed along the beach, month by month
How to read it: bars above the line are sand pushed north (thousands of cubic metres).
Which storms moved the most sand
How to read it: storms ranked by how much sand they pushed north; the share of the year is on each bar.
Running total of sand moved
How to read it: the line climbs in steps; each step is a storm (orange bands).
When does the seabed move?
How to read it: each bar is a month: the share of hours waves were strong enough to roll fine sand on the seabed 12 m down.
Where the bottom water drifts
How to read it: the path a drop of dye would take if carried by the measured bottom current, out where the buoy sits (offshore of the surf zone). Near the bottom the water drifts slowly south, the opposite of the sand near shore: in a bay, deep water often returns the other way.
Why the beach angle matters
How to read it: the yearly amount for different beach directions (above zero = north). The dotted line is Camp Ellis; the answer flips if the beach faced east or further south.
How we measured it
Each hour, waves from the Camp Ellis buoy are bent and steepened toward shore (linear wave theory, straight depth contours) until they break, then fed into two standard sand-transport formulas (CERC and Kamphuis). The beach from the jetty to Ferry Beach faces about 65° (east-northeast). Potential transport there: about 174 thousand m³ per year to the north (Kamphuis). The direction would flip for a beach facing more than 82°, so farther north, where the shore turns toward the east-southeast, this single buoy can't say. Seabed movement uses the Shields number for 0.2 mm sand.
Where does the river meet the sea?
Right at our Jordan Point buoy, and the meeting place moves twice a day.
Every rising tide pushes ocean water up the Saco; every falling tide the river pushes it back out. Press play to watch two real days at Jordan Point.
- In those two days the water at the buoy went from about 22% ocean water to 39%, and back, every tide.
- A typical tide swings the saltiness by about 9 units: from half river water to nearly pure ocean in about six hours.
- The bigger the tide, the further the ocean reaches: tides explain 81% of how big each day's swing is.
- The Saco has been running low, about 56% of normal lately, and less river water lets the sea reach further upstream.
Saco River flow vs normal
How to read it: the dashed line at 100% is normal for the date. The shaded strip is less than half of normal.
Where is the water salty?
How to read it: each buoy is coloured by its average saltiness over the last 30 days: darker = saltier ocean water.
Tide clock: salinity hour by hour
How to read it: each row is a day. Dark = salty ocean water. The dark bands slide right because high tide comes ~50 minutes later each day.
Saltiness at Jordan Point, day by day
How to read it: daily average. It drops when the river rises after rain.
Saco River flow
How to read it: daily flow at Cornish (USGS).
Bigger tides, bigger swings
How to read it: each dot is a day; bigger tides slide saltier water past the sensor.
A simple salinity model
How to read it: dotted line: a one-equation model driven by river flow and tides.
Are the four water-quality buoys really different?
How to read it: each dot is how different two buoys are on average; its line is the range we are confident in. Lines crossing the dark zero line mean we can't say they differ yet.
Estuary mixing calculator
How to use it: green values are measured; orange are guesses until the channel is surveyed.
Is there algae in the water?
A little, and it's at healthy, low levels.
Our sensors measure chlorophyll, the green pigment in microscopic algae. One fun twist: in bright sun, algae "squint" and glow less, so the sensor reads low at noon.
- At midday the reading drops to about 45% of the night-time value at Wood Island. The algae haven't gone anywhere.
- Night-time levels were "low" on NOAA's scale on 30 of 32 nights at Wood Island and 31 of 39 at Jordan Point; never high.
- At Jordan Point the saltiest water carried the most algae, so this fall the algae rode in from the bay.
The midday "dip"
How to read it: typical chlorophyll for each hour of the day. The yellow band is midday sun.
Algae night by night
How to read it: one dot per night. Green strip = NOAA "low", yellow = "medium".
Ocean water or river water?
How to read it: each box is Jordan Point's night-time chlorophyll for water of a given saltiness; boxes further right are saltier.
What about the marsh, the woods and the wind?
The marsh breathes with the tide, and the forest soil breathes with the sun.
Water floods into Biddeford Pool Marsh faster than it drains out, which helps the marsh trap mud and keep up with rising seas. In the woods, each day's warmth sinks into the soil and fades.
- The tide explains 89% of the marsh's water level; the rest is weather.
- A day's warmth takes about 4.5 hours to sink each 10 cm into the soil, and is almost gone by 45 cm.
The marsh's tide, measured vs predicted
How to read it: solid = measured water; dotted = the tide predicted from Moon and Sun alone.
The daily heat pulse in the soil
How to read it: each row is a depth. Red = warmer than that depth's daily average. Follow a red patch down: it fades and arrives later.
The tide's "beats"
How to read it: how strong each regular tidal rhythm is in the marsh.
Where does the wind come from?
How to read it: each petal points to where the wind comes from; longer = more often, darker = stronger.
Does the radar agree with the wind?
How to read it: grey dots are single scans; the orange line is the typical roughness at each wind speed.
Want every number?
The full technical page has all 27 analyses with their methods, assumptions and uncertainty.