Ocean Temperatures Hit Record Highs for October
Sea-surface temperatures set global records for October as a strong El Niño event takes hold in the Pacific.
Updated on Nov. 6, 2026 in Severe Weather
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Sea-surface temperatures set fresh record highs globally for any October, with several regions around the Australian coast also registering record October highs. The warmth is being driven by long-run climate change combined with a developing El Niño event in the Pacific.
Why it matters
Just over 90% of excess heat trapped by greenhouse gases ends up in the oceans, so sustained ocean warming affects marine ecosystems worldwide. Some reefs already show low-level coral bleaching, and forecasts suggest the Great Barrier Reef could face another large bleaching event.
The record readings come from US NOAA sea-surface data analysed by Australia's Bureau of Meteorology, showing October records globally and along parts of the Australian coast. Forecasters have not yet determined how far the warming will extend into the Coral Sea and Great Barrier Reef region during the coming months.
The players
US National Oceanic and Atmospheric Administration (NOAA)
NOAA is the US federal agency responsible for monitoring oceans and atmosphere, and its sea-surface temperature data underpins the record readings reported here.
Australian Bureau of Meteorology
Australia's national weather service analysed the NOAA data and tracks El Niño and sea temperature conditions across the Australian region.
The details
Long-run background warming from climate change has been compounded by a large El Niño event in the central to eastern equatorial Pacific. Sea-surface temperatures have been rising for decades, and the Tasman Sea and southern Australian regions recorded their warmest Octobers on record.
Timeline
Last month (October 2026): Sea-surface temperatures set global October records while tropical Australian waters were warmer than average but not at record levels.
November or December 2026: The El Niño event is forecast to peak.
Autumn 2027: The El Niño is expected to continue into this period.
Seasonal Patterns
Sea-surface temperatures have risen for decades, and the record October readings extend that documented trend by setting new highs for the month. The current figures are amplified by a strong El Niño event that is expected to peak in November or December and persist into autumn 2027.
Coastal communities and reef-dependent businesses should monitor forecasts from national weather services as the El Niño develops. Readers following reef health can track bleaching alerts issued by marine monitoring agencies as conditions evolve.
The takeaway
Ocean warming is cumulative, and each record year builds on the last, so the long-term trend matters more than any single month. Staying informed through official forecasts gives coastal residents and marine stakeholders the earliest warning of how conditions may affect reefs and fisheries.
What happens next
The El Niño event is forecast to peak in November or December 2026 and continue into autumn 2027, and sea-surface temperatures across the Australian region are expected to keep warming over the coming months.
Further reading
For more on how these ocean conditions fit into wider weather patterns, explore Severe Weather.
Source note: This article includes information reported by RenewEconomy.
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