# Coral Bleaching Heat Stress Today

> Explore NOAA’s latest global coral bleaching heat-stress maps, including HotSpots, Degree Heating Weeks, and Bleaching Alert Areas.

Canonical URL: https://www.argo.net/coral-bleaching-heat-stress-today/
Byline: ARGO.net Editorial Team
Published: 2026-08-01T21:46:22+00:00
Categories: Oceans, Biology, Live

![Sea fan coral growing on an underwater reef](https://www.argo.net/wp-content/uploads/2026/08/gorgonian_coral_reef_underwater.jpg)

Live data

## Coral Bleaching Heat Stress Today

      Data updated August 5, 2026 4:30 am GMT+0000   Source data dated August 4, 2026   Editorially updated August 1, 2026      ![NOAA global coral bleaching HotSpot map](https://www.argo.net/wp-content/uploads/argo-living/noaa-coral-hotspot.png)

*HotSpot: where sea surface temperature exceeds the expected warm-season maximum.*

  ![NOAA global Degree Heating Week map](https://www.argo.net/wp-content/uploads/argo-living/noaa-coral-degree-heating-weeks.png)

*Degree Heating Week: accumulated heat stress over the previous 12 weeks.*

  ![NOAA global coral bleaching alert area map](https://www.argo.net/wp-content/uploads/argo-living/noaa-coral-bleaching-alert-area.png)

*Bleaching Alert Area: NOAA’s combined current heat-stress classification.*

**How to read these maps:** A HotSpot shows current thermal stress; Degree Heating Weeks measure its recent accumulation. Heat stress raises bleaching risk but does not by itself confirm bleaching at a particular reef.

 **Primary source:** [NOAA Coral Reef Watch](https://coralreefwatch.noaa.gov/product/5km/).

## Three views of coral heat stress

The maps come from [NOAA Coral Reef Watch](https://coralreefwatch.noaa.gov/product/5km/) and describe related but different parts of thermal stress.

- **HotSpot** shows where current sea surface temperature exceeds the expected warm-season maximum.
- **Degree Heating Week** accumulates meaningful heat stress over the previous 12 weeks.
- **Bleaching Alert Area** combines current and accumulated stress into NOAA’s operational alert categories.

## How often it updates

ARGO.net checks for new NOAA maps every six hours. Coral Reef Watch products are based on satellite-derived sea surface temperatures and are generally updated daily.

## What the maps can—and cannot—tell us

Sustained marine heat raises the risk that corals expel their symbiotic algae and bleach. The maps estimate heat stress at a broad scale; they do not confirm the condition, mortality, or recovery of a particular reef. Local depth, currents, clouds, water quality, species composition, and prior exposure can change the outcome.

## Use alongside field reports

For a complete picture, combine these maps with local monitoring, reef surveys, management notices, and regional forecasts. Bleaching is a stress response, not automatically coral death, although long or intense events can cause extensive mortality.