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.

January: Summer Lull with Brief Windows

January at Grumari is typical of the austral summer. The average swell height sits at 0.9m with a period of 9.6 seconds, indicating mostly small, short-period energy. The dominant swell directions are SSE (28.7%) and S (27.9%), which are favorable for the spot's SSE exposure, followed by SE (22.2%) and ESE (16.8%). This mix means the cove does catch some swell, but heights rarely exceed 1.5m (only ~4% of the time). The wind is ideal 44% of the time, primarily from the N and NNE quadrants (N at 6.6%, NNE at 10.3%, NE at 11.2%). However, the trade winds from E and ENE are also active (E at 10.2%, ENE at 11.8%), creating onshore conditions that can chop up the waves. When a land breeze from the north sets in overnight and early morning, the weak SSE swell can be fun-sized, but expect groveling conditions on a shortboard. Choppy and messy sections prevail when the afternoon sea breeze fills in.