Grumari Beach Water Temperature & Swim Forecast
Undeveloped nature-reserve beach.
Pleasant water with a light chop and a light breeze — good swimming conditions.
Model estimate · modelled, not a buoy measurement. How accurate is this?
Location
Grumari 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.
Shorty 2mm
At 21.4°C a 2mm shorty keeps surfers warm; lap swimmers can usually skip the neoprene.
Recommendation tuned for Grumari Beach's current water temperature. Individual tolerance, wind chill, and session length all matter — when in doubt, size up.
Grumari Beach swimming conditions summary
- Water temperature
- 21.4°C
- Water feels
- Pleasant
- Swimmable today
- Yes — comfortable for most swimmers
- Swim conditions score
- 83/100 · Excellent
- Wetsuit needed
- Shorty 2mm
- Air temperature
- —
- Waves
- —
- Wind
- —
- UV index
- —
- Average sea temperature (September)
- 21.0 °C
- Warmest months to swim
- July, August, September
At 21.4°C a 2mm shorty keeps surfers warm; lap swimmers can usually skip the neoprene. 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 Grumari Beach right now?
The sea at Grumari Beach is currently 21.4°C — good 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 Grumari Beach next week?
Based on long-term September averages and the latest marine model, expect the sea around Grumari Beach to sit close to 19.6°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 Grumari Beach?
July – August – September are typically the warmest months to swim at Grumari Beach, with sea temperatures at their seasonal peak.
Do I need a wetsuit at Grumari Beach?
With water currently at 21.4°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 Grumari Beach today?
The sea is currently 21.4°C — excellent swimming conditions. Most swimmers will find it pleasant.
- • Located in Rio de Janeiro, Brazil (Atlantic Ocean).
- • Best suited to confident swimmers and watersports.
- • 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 Grumari Beach
The sea in Grumari Beach peaks in August, when the water averages around 21°C.
The main swimming season runs from July – September, when surface temperatures stay comfortable for extended sessions.
On average, 3 months a year sit above 20°C — the threshold most swimmers describe as pleasant without a wetsuit.
Shoulder months like June and October are noticeably cooler but often quieter, with fewer crowds and steadier weather.
Outside peak season the water drops toward 14°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable.
The coldest month is typically January at around 14°C, when cold-water swimmers dominate the coast.
Grumari Beach sea temperature history
Long-term climatology for Grumari Beach shows an annual mean sea temperature of 17°C, ranging from 14°C in winter to 21°C at the summer peak.
The seasonal swing is roughly 7°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 Grumari 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.
Grumari Beach sea temperature: frequently asked questions
What is the warmest month to swim in Grumari Beach?
August is the warmest month in Grumari Beach, when the sea averages about 21°C. Late-season warmth often persists a few weeks after peak.
When is the sea coldest in Grumari Beach?
The coldest month in Grumari Beach is typically January, when the water averages around 14°C. Cold-water swimmers and surfers dominate this period.
When can you swim in Grumari Beach without a wetsuit?
The main swimming season in Grumari Beach runs from July – September — about 3 months 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 Grumari Beach?
Outside peak summer the water in Grumari Beach drops toward 14°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 Grumari Beach?
The long-term annual mean sea temperature in Grumari Beach is about 17°C, based on multi-decadal climatology of the surrounding waters.
How do I check the current sea temperature in Grumari Beach?
The live reading at the top of this page shows the current sea temperature in Grumari 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: Jul – Aug – Sep
| Month | Sea | Comfort |
|---|---|---|
| Jan | 14°C | Bracing |
| Feb | 14°C | Bracing |
| Mar | 14°C | Bracing |
| Apr | 15°C | Bracing |
| May | 16°C | Bracing |
| Jun | 18°C | Pleasant |
| Jul | 20°C | Pleasant |
| Aug ⭐ | 21°C | Pleasant |
| Sep | 21°C | Pleasant |
| Oct | 19°C | Pleasant |
| Nov | 17°C | Bracing |
| Dec | 15°C | Bracing |
Nearby beaches
The closest coastline, with live water temperatures.