Portland — Water Temperature, Sea Conditions & Trends
This page provides clear and up-to-date information about water temperature for Portland (Maine, United States). It includes the current water temperature, daily data for the last month presented in a simple chart, and a 7-day forecast. The page also compares today’s value with typical averages for this period, shows usual monthly ranges during the year, and lists nearby beaches with short descriptions. Local weather for the next few days and general details about Portland help you plan your visit and choose the best time for swimming.
Current Water Temperature
Water temperature in Portland in the Atlantic Ocean today is 16°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 60°F (15°C) to 65°F (18°C). The water is comfortable for most people, making it an ideal range for water sports enthusiasts. The temperature does not cause significant discomfort, and swimming will be pleasant for the majority. However, it's important to remember that prolonged exposure to the water can still lead to cooling, so it's essential to monitor the time spent in the water, especially for children or elderly people.
It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Water temperature in Portland has risen over the last week and month. Currently, the sea water at this location is slightly warmer than average for this day in previous years.
According to our forecast, Water temperature in Portland will be 13.9°C in the next 7 days. See the table below for daily data for the upcoming week.
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| JUN 6 | 11.9°C | 11.5°C | |
| JUN 7 | 12.1°C | 12.5°C | |
| JUN 8 | 13.0°C | 11.5°C | |
| JUN 9 | 12.8°C | 13.0°C | |
| JUN 10 | 12.9°C | 13.3°C | |
| JUN 11 | 13.6°C | 13.3°C | |
| JUN 12 | 13.7°C | 13.5°C | |
| JUN 13 | 14.7°C | 13.8°C | |
| JUN 14 | 15.6°C | 13.8°C | 15.6°C |
| JUN 15 | 12.3°C | 15.4°C | |
| JUN 16 | 12.3°C | 15.1°C | |
| JUN 17 | 12.5°C | 14.9°C | |
| JUN 18 | 13.0°C | 14.6°C | |
| JUN 19 | 13.5°C | 14.4°C | |
| JUN 20 | 13.0°C | 14.1°C | |
| JUN 21 | 13.5°C | 13.9°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Water temperature data for this location is gathered from various sources, including buoys and satellite sea and ocean surface maps provided by the NOAA agency. We also incorporate data from local authorities in each specific location worldwide to ensure more accurate temperature readings.
Annual Water Temperature Overview by Month
Monthly Water Temp Ranges
Annual Water Temperature Trend
Portland, Maine sits on the inner edge of Casco Bay and experiences a marked seasonal swing in coastal water temperatures. Winter surface waters commonly hover near freezing, roughly 0–4°C, while spring brings a gradual rise into the single digits, often about 3–10°C by late spring. Summer is the warmest period for swimming, with typical sea surface temperatures in June through August ranging from around 10–18°C and occasional sheltered pockets reaching nearer 20°C during heat anomalies. In autumn the water cools again, usually falling to roughly 8–12°C as the air chills and storms stir the bay. Tidal flows, wind-driven currents and the deeper Gulf of Maine influence these values, so short-term variability and cool upwellings are common even in summer.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 2°C | 4°C | 6°C |
| February | 1°C | 3°C | 6°C |
| March | 1°C | 3°C | 6°C |
| April | 2°C | 5°C | 8°C |
| May | 4°C | 8°C | 13°C |
| June | 8°C | 12°C | 17°C |
| July | 12°C | 15°C | 20°C |
| August | 13°C | 16°C | 20°C |
| September | 12°C | 15°C | 19°C |
| October | 8°C | 12°C | 17°C |
| November | 7°C | 10°C | 14°C |
| December | 3°C | 8°C | 11°C |
* Click on a month to view detailed water temperature data.
Portland: Weather Forecast
June 15
June 16
June 17
June 18
Location, Beaches & Local Information
Nearby Beaches & Facilities
East End Beach
Martin Point Trail
Willard Beach
West Shore Sandy Beach
Cliff House Beach
Fowler Beach
Robinson Woods Preserve
Andrews Beach
Swimming Conditions
Swimming and beach-going around Portland reflect those temperature patterns, offering bracing cold-water swims for hardy visitors as well as more comfortable conditions in peak summer. Public city beaches and nearby state parks provide sandy shorelines, while protected coves and harbor areas can be relatively calmer and slightly warmer on sunny days. Lifeguard coverage and amenities vary by site and season, so swimmers should check local services and water-quality postings before entering. Wetsuits are routine for many open-water swimmers here, and calmer days favor kayaking, paddleboarding and island-hopping that allow short swims from sheltered landings. Regardless of the season, awareness of tides, currents and changing weather is important for safe enjoyment of the coastal waters.