Surf Forecast for Grumari
type: Dataset
description: 10-day surf forecast with Strike Scores for Grumari, Rio de Janeiro, RJ, Brazil
about: Grumari
  type: TouristAttraction
  geo: GeoCoordinates
    latitude: -23.05
    longitude: -43.5333
  description: Grumari is Rio de Janeiro's most pristine surf beach, an environmental reserve where big wave legend Carlos Burle has called his favorite local spot. The beach is protected from development, creating a natural sanctuary just an hour from the city center. The waves are versatile, handling various swell directions and producing both lefts and rights along the beach. Access is controlled and parking limited, which keeps the crowds manageable even on good days.
summary:
  best day:
    date: 2026-08-09
    score: 76
    category: Good
    explanation: Best day in the forecast: 2026-08-09 with a score of 76/100 (Good)
  firing days count: 0
  overall recommendation: Fair recommendation: Grumari has 3 Good days but no Firing days. Decent for a local session.
forecasts:
  date: 2026-08-05
  day index: 0
  strike score:
    final score: 72
    category: Good
    category emoji: ✅
    confidence: 1
    confidence explanation: Very high confidence (0-1 day forecast)
    breakdown:
      swell direction:
        score: 25
        out of: 25
        explanation: Perfect alignment: Swell from 180° is within 5° of optimal 180°.
      swell size:
        score: 12
        out of: 25
        explanation: Marginal size: 1.3m is 0.4m from ideal 1.7m.
      swell period:
        score: 23
        out of: 25
        explanation: Good period: 13s is 93% of ideal 14s. Clean, powerful groundswell.
      wind:
        score: 16
        out of: 25
        explanation: Moderate offshore: 11 km/h from 23° (NNE). Still grooming but noticeable wind.
    adjustments:
      wind history:
        adjustment: 0
        groomed: false
        morning sickness: false
        explanation: No significant wind history adjustment.
      windswell penalty:
        adjustment: 0
        windswell degraded: false
        explanation: Groundswell-dominant conditions (clean, long-period waves).
      secondary swell bonus:
        adjustment: 0
        explanation: No secondary swell bonus.
    summary: Good surfable conditions at Grumari. 1.3m swell from 180° with manageable wind. Solid session guaranteed.
  conditions:
    swell:
      height m: 1.3
      height ft: 4.3
      direction degrees: 180
      direction cardinal: S
      period s: 13
      explanation: 1.3m (4.3ft) swell from 180° (S) at 13s period
    wind:
      speed kmh: 11
      speed mph: 6.8
      direction degrees: 23
      direction cardinal: NNE
      explanation: 11 km/h (7 mph) from 23° (NNE)
    secondary swell:
      height m: 0.6
      direction degrees: 115
      direction cardinal: ESE
      period s: 6
forecasts:
  date: 2026-08-06
  day index: 1
  strike score:
    final score: 7
    category: Poor
    category emoji: 💤
    confidence: 1
    confidence explanation: Very high confidence (0-1 day forecast)
    breakdown:
      swell direction:
        score: 0
        out of: 25
        explanation: No alignment: Swell from 95° is outside workable range 135°-225°. Wrong swell direction for this spot.
      swell size:
        score: 11
        out of: 25
        explanation: Marginal size: 1.2m is 0.5m from ideal 1.7m.
      swell period:
        score: 4
        out of: 25
        explanation: Short period: 9s is below minimum 10s. Windswell-dominated (choppy, weak waves).
      wind:
        score: 7
        out of: 25
        explanation: Moderate offshore: 15 km/h from 4° (N). Still grooming but noticeable wind.
    adjustments:
      wind history:
        adjustment: 0
        groomed: false
        morning sickness: false
        explanation: No significant wind history adjustment.
      windswell penalty:
        adjustment: 0
        windswell degraded: false
        explanation: Groundswell-dominant conditions (clean, long-period waves).
      secondary swell bonus:
        adjustment: 0
        explanation: No secondary swell bonus.
    summary: Poor conditions at Grumari. Either swell direction (95°), size (1.2m), or wind (15 km/h from 4°) is unfavorable. Consider other spots or wait for better conditions.
  conditions:
    swell:
      height m: 1.2
      height ft: 3.9
      direction degrees: 95
      direction cardinal: E
      period s: 9
      explanation: 1.2m (3.9ft) swell from 95° (E) at 9s period
    wind:
      speed kmh: 15
      speed mph: 9.3
      direction degrees: 4
      direction cardinal: N
      explanation: 15 km/h (9 mph) from 4° (N)
    secondary swell:
      height m: 0.6
      direction degrees: 164
      direction cardinal: SSE
      period s: 8
    windswell:
      height m: 0.3
      period s: 2
      explanation: Local wind-generated waves (choppy, short-period)
forecasts:
  date: 2026-08-07
  day index: 2
  strike score:
    final score: 11
    category: Poor
    category emoji: 💤
    confidence: 0.95
    confidence explanation: High confidence (2-3 day forecast)
    breakdown:
      swell direction:
        score: 0
        out of: 25
        explanation: No alignment: Swell from 89° is outside workable range 135°-225°. Wrong swell direction for this spot.
      swell size:
        score: 9
        out of: 25
        explanation: Marginal size: 1.0m is 0.7m from ideal 1.7m.
      swell period:
        score: 2
        out of: 25
        explanation: Short period: 8s is below minimum 10s. Windswell-dominated (choppy, weak waves).
      wind:
        score: 23
        out of: 25
        explanation: Moderate offshore: 18 km/h from 325° (NW). Still grooming but noticeable wind.
    adjustments:
      wind history:
        adjustment: 0
        groomed: false
        morning sickness: false
        explanation: No significant wind history adjustment.
      windswell penalty:
        adjustment: 0
        windswell degraded: false
        explanation: Groundswell-dominant conditions (clean, long-period waves).
      secondary swell bonus:
        adjustment: 0
        explanation: No secondary swell bonus.
    summary: Poor conditions at Grumari. Either swell direction (89°), size (1.0m), or wind (18 km/h from 325°) is unfavorable. Consider other spots or wait for better conditions.
  conditions:
    swell:
      height m: 1
      height ft: 3.3
      direction degrees: 89
      direction cardinal: E
      period s: 8
      explanation: 1.0m (3.3ft) swell from 89° (E) at 8s period
    wind:
      speed kmh: 18
      speed mph: 11.2
      direction degrees: 325
      direction cardinal: NW
      explanation: 18 km/h (11 mph) from 325° (NW)
    secondary swell:
      height m: 0.5
      direction degrees: 169
      direction cardinal: S
      period s: 8
    windswell:
      height m: 0.3
      period s: 2
      explanation: Local wind-generated waves (choppy, short-period)
provider: Strike Mission
date published: 2026-08-05T03:15:59.796Z
temporal coverage: 2026-08-05/2026-08-14
data sources: Open-Meteo Marine API (swell/wave data)
data sources: Open-Meteo Weather API (wind/weather data)

date: 2026-08-08
day index: 3
strike score:
  final score: 38
  category: Poor
  category emoji: 💤
  confidence: 0.92
  confidence explanation: High confidence (2-3 day forecast)
  breakdown:
    swell direction:
      score: 14
      out of: 25
      explanation: Moderate alignment: Swell from 197° is 17° off optimal 180°, workable but not ideal.
    swell size:
      score: 17
      out of: 25
      explanation: Marginal size: 1.7m is 0.0m from ideal 1.7m.
    swell period:
      score: 8
      out of: 25
      explanation: Moderate period: 11s meets minimum 10s but below ideal 14s. Some groundswell energy present.
    wind:
      score: 4
      out of: 25
      explanation: Onshore/cross-shore: 13 km/h from 88° (E). Destroying wave quality. Offshore range: 270°-45°.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Poor conditions at Grumari. Either swell direction (197°), size (1.7m), or wind (13 km/h from 88°) is unfavorable. Consider other spots or wait for better conditions.
conditions:
  swell:
    height m: 1.7
    height ft: 5.6
    direction degrees: 197
    direction cardinal: SSW
    period s: 11
    explanation: 1.7m (5.6ft) swell from 197° (SSW) at 11s period
  wind:
    speed kmh: 13
    speed mph: 8.1
    direction degrees: 88
    direction cardinal: E
    explanation: 13 km/h (8 mph) from 88° (E)
  secondary swell:
    height m: 0.4
    direction degrees: 148
    direction cardinal: SSE
    period s: 7

date: 2026-08-09
day index: 4
strike score:
  final score: 76
  category: Good
  category emoji: ✅
  confidence: 0.89
  confidence explanation: Moderate confidence (4-5 day forecast)
  breakdown:
    swell direction:
      score: 16
      out of: 25
      explanation: Moderate alignment: Swell from 194° is 14° off optimal 180°, workable but not ideal.
    swell size:
      score: 19
      out of: 25
      explanation: Marginal size: 2.3m is 0.6m from ideal 1.7m.
    swell period:
      score: 25
      out of: 25
      explanation: Perfect period: 14s is at or above ideal 14s. Long-period groundswell with maximum power.
    wind:
      score: 21
      out of: 25
      explanation: Strong offshore: 21 km/h from 303° (WNW). Grooming but may make paddling difficult.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Good surfable conditions at Grumari. 2.3m swell from 194° with moderate wind. Solid session guaranteed.
conditions:
  swell:
    height m: 2.3
    height ft: 7.5
    direction degrees: 194
    direction cardinal: SSW
    period s: 14
    explanation: 2.3m (7.5ft) swell from 194° (SSW) at 14s period
  wind:
    speed kmh: 21
    speed mph: 13.0
    direction degrees: 303
    direction cardinal: WNW
    explanation: 21 km/h (13 mph) from 303° (WNW)
  secondary swell:
    height m: 0.6
    direction degrees: 110
    direction cardinal: ESE
    period s: 7
  windswell:
    height m: 0.5
    period s: 3
    explanation: Local wind-generated waves (choppy, short-period)

date: 2026-08-10
day index: 5
strike score:
  final score: 55
  category: Fair
  category emoji: 😐
  confidence: 0.86
  confidence explanation: Moderate confidence (4-5 day forecast)
  breakdown:
    swell direction:
      score: 23
      out of: 25
      explanation: Good alignment: Swell from 183° is 3° off optimal 180°, still within prime range.
    swell size:
      score: 18
      out of: 25
      explanation: Marginal size: 2.4m is 0.7m from ideal 1.7m.
    swell period:
      score: 14
      out of: 25
      explanation: Moderate period: 12s meets minimum 10s but below ideal 14s. Some groundswell energy present.
    wind:
      score: 5
      out of: 25
      explanation: Onshore/cross-shore: 12 km/h from 123° (ESE). Destroying wave quality. Offshore range: 270°-45°.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Surfable but not special at Grumari. The 2.4m swell from 183° is workable, but conditions aren't ideal. Fine if you're local, but not worth a dedicated trip.
conditions:
  swell:
    height m: 2.4
    height ft: 7.9
    direction degrees: 183
    direction cardinal: S
    period s: 12
    explanation: 2.4m (7.9ft) swell from 183° (S) at 12s period
  wind:
    speed kmh: 12
    speed mph: 7.5
    direction degrees: 123
    direction cardinal: ESE
    explanation: 12 km/h (7 mph) from 123° (ESE)
  secondary swell:
    height m: 0.7
    direction degrees: 175
    direction cardinal: S
    period s: 11

date: 2026-08-11
day index: 6
strike score:
  final score: 26
  category: Poor
  category emoji: 💤
  confidence: 0.83
  confidence explanation: Low confidence (6-7 day forecast)
  breakdown:
    swell direction:
      score: 18
      out of: 25
      explanation: Moderate alignment: Swell from 190° is 10° off optimal 180°, workable but not ideal.
    swell size:
      score: 3
      out of: 25
      explanation: Too big: 3.5m exceeds maximum 2.5m. Risk of closeouts.
    swell period:
      score: 14
      out of: 25
      explanation: Moderate period: 12s meets minimum 10s but below ideal 14s. Some groundswell energy present.
    wind:
      score: 1
      out of: 25
      explanation: Onshore/cross-shore: 20 km/h from 190° (S). Destroying wave quality. Offshore range: 270°-45°.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Poor conditions at Grumari. Either swell direction (190°), size (3.5m), or wind (20 km/h from 190°) is unfavorable. Consider other spots or wait for better conditions.
conditions:
  swell:
    height m: 3.5
    height ft: 11.5
    direction degrees: 190
    direction cardinal: S
    period s: 12
    explanation: 3.5m (11.5ft) swell from 190° (S) at 12s period
  wind:
    speed kmh: 20
    speed mph: 12.4
    direction degrees: 190
    direction cardinal: S
    explanation: 20 km/h (12 mph) from 190° (S)
  windswell:
    height m: 0.8
    period s: 4
    explanation: Local wind-generated waves (choppy, short-period)

date: 2026-08-12
day index: 7
strike score:
  final score: 38
  category: Poor
  category emoji: 💤
  confidence: 0.8
  confidence explanation: Low confidence (6-7 day forecast)
  breakdown:
    swell direction:
      score: 17
      out of: 25
      explanation: Moderate alignment: Swell from 191° is 11° off optimal 180°, workable but not ideal.
    swell size:
      score: 9
      out of: 25
      explanation: Too big: 2.9m exceeds maximum 2.5m. Risk of closeouts.
    swell period:
      score: 8
      out of: 25
      explanation: Moderate period: 11s meets minimum 10s but below ideal 14s. Some groundswell energy present.
    wind:
      score: 13
      out of: 25
      explanation: Onshore/cross-shore: 8 km/h from 145° (SE). Destroying wave quality. Offshore range: 270°-45°.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Poor conditions at Grumari. Either swell direction (191°), size (2.9m), or wind (8 km/h from 145°) is unfavorable. Consider other spots or wait for better conditions.
conditions:
  swell:
    height m: 2.9
    height ft: 9.5
    direction degrees: 191
    direction cardinal: S
    period s: 11
    explanation: 2.9m (9.5ft) swell from 191° (S) at 11s period
  wind:
    speed kmh: 8
    speed mph: 5.0
    direction degrees: 145
    direction cardinal: SE
    explanation: 8 km/h (5 mph) from 145° (SE)

date: 2026-08-13
day index: 8
strike score:
  final score: 62
  category: Fair
  category emoji: 😐
  confidence: 0.8
  confidence explanation: Very low confidence (8-10 day forecast, conditions may change)
  breakdown:
    swell direction:
      score: 21
      out of: 25
      explanation: Good alignment: Swell from 185° is 5° off optimal 180°, still within prime range.
    swell size:
      score: 15
      out of: 25
      explanation: Too big: 2.6m exceeds maximum 2.5m. Risk of closeouts.
    swell period:
      score: 23
      out of: 25
      explanation: Good period: 13s is 93% of ideal 14s. Clean, powerful groundswell.
    wind:
      score: 8
      out of: 25
      explanation: Onshore/cross-shore: 11 km/h from 76° (ENE). Destroying wave quality. Offshore range: 270°-45°.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Surfable but not special at Grumari. The 2.6m swell from 185° is workable, but conditions aren't ideal. Fine if you're local, but not worth a dedicated trip.
conditions:
  swell:
    height m: 2.6
    height ft: 8.5
    direction degrees: 185
    direction cardinal: S
    period s: 13
    explanation: 2.6m (8.5ft) swell from 185° (S) at 13s period
  wind:
    speed kmh: 11
    speed mph: 6.8
    direction degrees: 76
    direction cardinal: ENE
    explanation: 11 km/h (7 mph) from 76° (ENE)
  secondary swell:
    height m: 0.5
    direction degrees: 124
    direction cardinal: SE
    period s: 9

date: 2026-08-14
day index: 9
strike score:
  final score: 72
  category: Good
  category emoji: ✅
  confidence: 0.8
  confidence explanation: Very low confidence (8-10 day forecast, conditions may change)
  breakdown:
    swell direction:
      score: 25
      out of: 25
      explanation: Perfect alignment: Swell from 180° is within 5° of optimal 180°.
    swell size:
      score: 17
      out of: 25
      explanation: Marginal size: 2.5m is 0.8m from ideal 1.7m.
    swell period:
      score: 25
      out of: 25
      explanation: Perfect period: 14s is at or above ideal 14s. Long-period groundswell with maximum power.
    wind:
      score: 10
      out of: 25
      explanation: Onshore/cross-shore: 10 km/h from 82° (E). Destroying wave quality. Offshore range: 270°-45°.
  adjustments:
    wind history:
      adjustment: 0
      groomed: false
      morning sickness: false
      explanation: No significant wind history adjustment.
    windswell penalty:
      adjustment: 0
      windswell degraded: false
      explanation: Groundswell-dominant conditions (clean, long-period waves).
    secondary swell bonus:
      adjustment: 0
      explanation: No secondary swell bonus.
  summary: Good surfable conditions at Grumari. 2.5m swell from 180° with manageable wind. Solid session guaranteed.
conditions:
  swell:
    height m: 2.5
    height ft: 8.2
    direction degrees: 180
    direction cardinal: S
    period s: 14
    explanation: 2.5m (8.2ft) swell from 180° (S) at 14s period
  wind:
    speed kmh: 10
    speed mph: 6.2
    direction degrees: 82
    direction cardinal: E
    explanation: 10 km/h (6 mph) from 82° (E)

Strike Mission
type: Organization