Grumari - surf spot statistics

Best Surf Season (May - August)

During the Southern Hemisphere winter, Grumari comes alive as a series of strong cold fronts and low-pressure systems track across the South Atlantic, firing long-period swell from the S and SSW quadrants directly into the beach's SSE-facing exposure. Average wave heights climb to 1.2-1.3m with periods consistently above 10 seconds, often reaching 11 seconds. The South Atlantic high-pressure system strengthens, promoting offshore winds from the N and NW quadrants a majority of the time. This combination produces clean, powerful surf that is both rippable and sometimes pumping. The highest percentage of ideal wind occurs in June (55%) and July (53%), making these the prime months for consistent sessions.

Fair Surf Season (March - April & September - October)

As the seasons transition, the swell window remains active but becomes more variable. March and April still enjoy robust S and SSE swell from late-season storms, with average heights around 1.0-1.2m and periods in the 10-second range. Wind patterns become less reliable, with increasing influence of the trade winds from the E and ENE, which can degrade conditions. September and October see a similar dynamic: the South Atlantic still generates sizable groundswell, but the frequency of ideal offshore winds drops to 37% and 31% respectively. This is a time of trade-offs—when the wind cooperates, the surf can be excellent, but those windows are narrower.

Low Surf Season (November - February)

The austral summer brings a lull in Southern Ocean storm activity. Average swell heights drop to 0.9-1.0m, and the dominant swell shifts eastwards with more ESE and SE energy that struggles to wrap effectively into the cove. Periods decrease to the 9-10 second range, resulting in less powerful waves. The trade wind regime dominates, with onshore E to ENE winds blowing 20-30% of the time, chopping up the surface. Offshore winds from the N and NW are less frequent, though they do occur. February stands out with a slightly higher ideal wind percentage (47%), but the smaller swell size limits quality. It's a time for smaller boards and patience.

March: Transition Month with Building Swell

March marks a noticeable uptick in surf quality as autumn begins. Average swell height rises to 1.0m and period lengthens to 10.4s, signaling the return of more organized groundswell. The swell direction shifts notably: SSE (36.4%) and S (30.2%) dominate, with SE still present at 24.9%. This increased S component is direct and powerful, and heights in the 1-1.5m range become more common (over 30% of the time). Ideal wind sits at 43%, with offshore quadrants from N (5.6%), NNE (9.1%), and NE (10.4%) still holding, but the trade winds from ENE (10.4%) and E (10.4%) are equally strong. The result is a mix: on good days, the cove sees clean, rippable waves with occasional overhead sets; on others, onshore flow disrupts the surface. Patience pays off as the season transitions.