Marine Heatwave Live NZA Data Experiment, by Marulho ↗

How warm is the sea today?

A live dashboard tracking sea surface temperature (SST), 30-year anomaly, and marine-heatwave status across 12 NZ coastal regions — updated daily.

What's a marine heatwave?

Sea temperature in the warmest 10% of the 30-year record for at least 5 consecutive days. Slower and larger than a land heatwave, often invisible from shore — but linked to kelp forest die-off, mass marine mortality, and disrupted fisheries.

7 regions currently in marine heatwave conditions. Longest active event: 93 days in Otago (Severe category).

Latest observation: 2026-11-08 — live sea temperature from Open-Meteo Marine API — 30-year average from NOAA CoralTemp (1991–2020)

Sea temperature above the 30-year average.

Northland

Te Tai Tokerau

Off Bay of Islands

16.8°C

+0.6°C vs baseline

No active heatwave

60-day sea temperature trend for Northland: 2026-09-10 to 2026-11-08. Sea temperature ranged from 15.5°C to 17.3°C. 16 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 16.2° · heatwave threshold 17.2°
Active strong marine heatwave, day 5.

Hauraki Gulf

Tīkapa Moana

Strong

Off Auckland

18.2°C

+1.9°C vs baseline

Day 5 of heatwave · peak +1.9°C

60-day sea temperature trend for Hauraki Gulf: 2026-09-10 to 2026-11-08. Sea temperature ranged from 14.1°C to 18.2°C. 21 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 16.4° · heatwave threshold 17.4°
Sea temperature above the 30-year average.

Coromandel

Off Coromandel township

17.1°C

+0.8°C vs baseline

No active heatwave

60-day sea temperature trend for Coromandel: 2026-09-10 to 2026-11-08. Sea temperature ranged from 13.2°C to 17.1°C.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 16.3° · heatwave threshold 17.4°
Sea temperature in the warmest 10% for this time of year, but not yet a qualifying heatwave.

Bay of Plenty

Te Moana-a-Toi

Off Ōpōtiki

17.4°C

+1.4°C vs baseline

Above threshold — not yet ≥5 days

60-day sea temperature trend for Bay of Plenty: 2026-09-10 to 2026-11-08. Sea temperature ranged from 14.8°C to 17.4°C. 41 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 16.0° · heatwave threshold 17.2°
Sea temperature above the 30-year average.

East Cape

East of Te Araroa

16.0°C

+0.4°C vs baseline

No active heatwave

60-day sea temperature trend for East Cape: 2026-09-10 to 2026-11-08. Sea temperature ranged from 14.7°C to 16.2°C. 2 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 15.6° · heatwave threshold 16.4°
Sea temperature in the warmest 10% for this time of year, but not yet a qualifying heatwave.

Hawke's Bay / Wairarapa

Te Matau-a-Māui

Off Napier

16.2°C

+1.2°C vs baseline

Above threshold — not yet ≥5 days

60-day sea temperature trend for Hawke's Bay / Wairarapa: 2026-09-10 to 2026-11-08. Sea temperature ranged from 13.6°C to 16.2°C. 13 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 14.9° · heatwave threshold 16.0°
Active severe marine heatwave, day 5.

Marlborough Sounds

Severe

Pelorus Sound

15.7°C

+1.7°C vs baseline

Day 5 of heatwave · peak +1.7°C

60-day sea temperature trend for Marlborough Sounds: 2026-09-10 to 2026-11-08. Sea temperature ranged from 12.1°C to 15.7°C. 25 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 14.1° · heatwave threshold 14.9°
Active severe marine heatwave, day 30.

Golden Bay

Mohua

Severe

Mid-bay

16.0°C

+1.4°C vs baseline

Day 30 of heatwave · peak +1.9°C

60-day sea temperature trend for Golden Bay: 2026-09-10 to 2026-11-08. Sea temperature ranged from 12.8°C to 16.0°C. 29 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 14.5° · heatwave threshold 15.3°
Active extreme marine heatwave, day 38.

Kaikōura / East Coast South

Extreme

East of Kaikōura

15.3°C

+2.7°C vs baseline

Day 38 of heatwave · peak +2.7°C

60-day sea temperature trend for Kaikōura / East Coast South: 2026-09-10 to 2026-11-08. Sea temperature ranged from 11.3°C to 15.3°C. 45 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 12.6° · heatwave threshold 13.5°
Active severe marine heatwave, day 93.

Otago

Severe

East of the peninsula

13.0°C

+1.8°C vs baseline

Day 93 of heatwave · peak +1.8°C

60-day sea temperature trend for Otago: 2026-09-10 to 2026-11-08. Sea temperature ranged from 11.0°C to 13.0°C. 60 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 11.2° · heatwave threshold 12.2°
Active severe marine heatwave, day 36.

Fiordland

Te Rua-o-te-Moko

Severe

West of Milford

14.1°C

+1.8°C vs baseline

Day 36 of heatwave · peak +2.0°C

60-day sea temperature trend for Fiordland: 2026-09-10 to 2026-11-08. Sea temperature ranged from 12.3°C to 14.3°C. 55 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 12.3° · heatwave threshold 13.1°
Active severe marine heatwave, day 6.

Foveaux Strait

Te Ara-a-Kiwa

Severe

Between Bluff and Stewart Island

13.8°C

+1.7°C vs baseline

Day 6 of heatwave · peak +1.7°C

60-day sea temperature trend for Foveaux Strait: 2026-09-10 to 2026-11-08. Sea temperature ranged from 11.7°C to 13.8°C. 56 days above threshold.30-year seasonal climatology (1991–2020 NOAA CoralTemp): the historical mean SST for each day-of-year. The line slopes with the season.Marine heatwave threshold: the 90th percentile of historical SST for each day-of-year (Hobday et al. 2016, 1991–2020 baseline). SST above this line for ≥5 consecutive days is a heatwave.
30-yr baseline 12.0° · heatwave threshold 12.9°

About marine heatwaves

Past NZ events have stretched thousands of kilometres across the Tasman Sea. Documented impacts around Aotearoa and elsewhere include kelp forest die-off, mass mortality in marine life, lower dissolved oxygen, ocean acidification, disrupted fisheries and aquaculture, and shifts in where species can survive — sometimes compounding with land heatwaves and other climate extremes.

This page reports the data so anyone can see when local conditions cross into heatwave territory. Interpretation of what it means for any specific ecosystem belongs with marine biologists, not us.