Kalmus Beach Water Temperature & Swim Forecast
Windsurf Sound-side Cape-Cod beach.
Fresh water with a light chop and a light breeze — fresh conditions — a wetsuit is recommended.
Model estimate · modelled, not a buoy measurement. How accurate is this?
Location
Kalmus Beach on the map, with nearby beaches and live sea temperatures.
7-day forecast
Water, air, waves, wind and UV outlook for the week ahead.
3/2mm fullsuit
At 17.4°C a 3/2mm fullsuit is the standard wetsuit for surfing and watersports.
Recommendation tuned for Kalmus Beach's current water temperature. Individual tolerance, wind chill, and session length all matter — when in doubt, size up.
Kalmus Beach swimming conditions summary
- Water temperature
- 17.4°C
- Water feels
- Refreshing
- Swimmable today
- Yes, but fresh — short swims or a wetsuit
- Swim conditions score
- 64/100 · Fair
- Wetsuit needed
- 3/2mm fullsuit
- Air temperature
- —
- Waves
- —
- Wind
- —
- UV index
- —
- Average sea temperature (September)
- 18.0 °C
- Warmest months to swim
- July, August, September
At 17.4°C a 3/2mm fullsuit is the standard wetsuit for surfing and watersports. Model estimate. Water, wave, wind and UV values are Open-Meteo marine/weather model estimates, refreshed hourly — not buoy measurements.
Frequently asked questions
Can I swim at Kalmus Beach right now?
The sea at Kalmus Beach is currently 17.4°C — fresh swimming conditions. Most swimmers will find the water comfortable when it's above 22°C; below 18°C feels fresh and a wetsuit is recommended.
What will the sea temperature be at Kalmus Beach next week?
Based on long-term September averages and the latest marine model, expect the sea around Kalmus Beach to sit close to 15.1°C over the next 7 days. Check the live 7-day chart above for the exact daily outlook.
When is the best month to swim at Kalmus Beach?
July – August – September are typically the warmest months to swim at Kalmus Beach, with sea temperatures at their seasonal peak.
Do I need a wetsuit at Kalmus Beach?
With water currently at 17.4°C: above 22°C no wetsuit needed; 18–22°C a shorty is comfortable for long swims; 14–18°C a 3/2mm full suit; below 14°C a 4/3mm or thicker.
Can I swim at Kalmus Beach today?
The sea is currently 17.4°C — fair swimming conditions. Acclimatised swimmers will be most comfortable.
- • Located in Massachusetts, United States (Atlantic Ocean).
- • Family friendly with calm, accessible water.
- • Live data refreshed hourly from Open-Meteo Marine.
Monthly sea temperature averages
Tap any month to see what to expect — based on regional climatology.
Best time to swim in Kalmus Beach
The sea in Kalmus Beach peaks in August, when the water averages around 20°C.
The main swimming season runs from August, when surface temperatures stay comfortable for extended sessions.
On average, 1 month a year sit above 20°C — the threshold most swimmers describe as pleasant without a wetsuit.
Shoulder months like July and September are noticeably cooler but often quieter, with fewer crowds and steadier weather.
Outside peak season the water drops toward 8°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable.
The coldest month is typically February at around 3°C, when cold-water swimmers dominate the coast.
Kalmus Beach sea temperature history
Long-term climatology for Kalmus Beach shows an annual mean sea temperature of 11°C, ranging from 3°C in winter to 20°C at the summer peak.
The seasonal swing is roughly 17°C between the coldest and warmest month — a useful yardstick when comparing years or checking whether the current sea is running above or below average.
Recent decades have trended slightly warmer at Kalmus Beach, in line with regional sea-surface temperature records for the wider basin.
Monthly averages below are drawn from multi-decadal climatology and are updated as new observations arrive.
Kalmus Beach sea temperature: frequently asked questions
What is the warmest month to swim in Kalmus Beach?
August is the warmest month in Kalmus Beach, when the sea averages about 20°C. Late-season warmth often persists a few weeks after peak.
When is the sea coldest in Kalmus Beach?
The coldest month in Kalmus Beach is typically February, when the water averages around 3°C. Cold-water swimmers and surfers dominate this period.
When can you swim in Kalmus Beach without a wetsuit?
The main swimming season in Kalmus Beach runs from August — about 1 month a year when the sea sits above 20°C, the level most swimmers describe as pleasant without a wetsuit.
Do I need a wetsuit in Kalmus Beach?
Outside peak summer the water in Kalmus Beach drops toward 8°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable. In peak months most swimmers go without.
What is the average sea temperature in Kalmus Beach?
The long-term annual mean sea temperature in Kalmus Beach is about 11°C, based on multi-decadal climatology of the surrounding waters.
How do I check the current sea temperature in Kalmus Beach?
The live reading at the top of this page shows the current sea temperature in Kalmus Beach, updated hourly from marine buoy and satellite data. The 7-day forecast covers water, air, waves, wind and UV for the week ahead.
Year-round sea temperature
Best swim months: Aug
| Month | Sea | Comfort |
|---|---|---|
| Jan | 4°C | Cold |
| Feb | 3°C | Cold |
| Mar | 4°C | Cold |
| Apr | 6°C | Cold |
| May | 10°C | Cold |
| Jun | 15°C | Bracing |
| Jul | 19°C | Pleasant |
| Aug ⭐ | 20°C | Pleasant |
| Sep | 18°C | Pleasant |
| Oct | 14°C | Bracing |
| Nov | 10°C | Cold |
| Dec | 6°C | Cold |
Nearby beaches
The closest coastline, with live water temperatures.