Marine heatwaves
Where the ocean is running hot right now — the water-side ingredient this site tracks for rapid intensification.
SST observations: Jul 12, 2026 · NOAA OISST v2.1 · updated daily
Hover or tap the map to inspect a cell.
- Moderate
- Strong
- Severe
- Extreme
- Below threshold
- Land
Marine heatwave: sea surface temperature in the warmest 10% of the 1991–2020 baseline for 5+ consecutive days (Hobday et al. 2016); categories are multiples of that exceedance.
No active marine heatwaves in the tracked domain right now.
Methods
A cell is in a marine heatwave when its sea surface temperature exceeds the 90th percentile of a 1991–2020 climatological baseline for that calendar day, and has done so for at least 5 consecutive days (Hobday et al. 2016). The category — Moderate, Strong, Severe, Extreme — counts how many multiples of the gap between the baseline mean and that 90th-percentile threshold the current anomaly spans.
Sea surface temperature comes from NOAA OISST v2.1 (0.25°, daily, published at 1–2 days' latency); the 30-year baseline is computed offline from the same product. The 5-day persistence rule is tracked with a per-cell rolling counter updated once per OISST day. Anomalies are shown in 0.2 °C steps.
This map is observational context — satellite-derived sea surface temperature scored against a published definition. It is not a forecast. Official tropical cyclone forecasts and warnings come from the National Hurricane Center.