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The world is closing in on another year of extreme heat as global observations point to 2025 becoming one of the three hottest years on record.
The Copernicus Climate Change Service said October was the third hottest October ever measured and confirmed that the long rise in global temperatures is continuing in a period measured against the Paris Agreement limits of 1.5 degrees Celsius and well below 2°C.
Copernicus reported that the global average temperature in October reached 15.14°C. This was 0.70°C above the 1991 to 2020 average and 1.55°C above the pre-industrial period.
Copernicus said this was the first time since April that a monthly temperature anomaly again rose above 1.5°C. Although October 2025 remained cooler than the record month of October 2023, the agency expects the full year of 2025 to end as the second or third hottest year in the global record.
Copernicus added that the period from November 2024 to October 2025 reached an average of 1.5°C above pre-industrial levels. The agency now expects the 2023 to 2025 period to become the first three-year stretch in history to cross that threshold.
A separate update from the World Meteorological Organization placed 2025 within a broader pattern of record warmth.
The agency said the years from 2015 to 2025 will all rank as the warmest 11 years ever observed. The January to August period of 2025 recorded a global near-surface temperature 1.42°C above the pre-industrial average. WMO linked the latest figures to long-term warming, record levels of greenhouse gases, and rising ocean heat content.
WMO Secretary General Celeste Saulo said, “It will be virtually impossible to limit global warming to 1.5 degrees (Celsius) in the next few years without temporarily overshooting this target.” She added that it remains essential to bring temperatures back down later in the century.
United Nations Secretary General Antonio Guterres also referred to the update at the Belém Climate Summit, saying every year above 1.5 degrees will deepen inequalities and cause irreversible damage.
The WMO report outlines several indicators of accelerating change. Ocean heat content reached record levels in 2024 and continued to rise in 2025. More than 90% of the excess heat trapped in the climate system is absorbed by the oceans, contributing to intensifying tropical and subtropical storms, rapid sea ice loss, and long-term sea level rise.
Satellite measurements show that the rate of global sea level rise nearly doubled over the past three decades. The year 2024 marked the highest annual sea level ever recorded.
Arctic sea ice reached its lowest winter maximum on record in March 2025. Antarctic sea ice stayed well below average throughout the year and recorded the third-lowest extents for both its annual minimum and maximum.
Glaciers also recorded a third consecutive year of significant mass loss. The World Glacier Monitoring Service estimates that monitored glaciers lost 450 gigatonnes of ice in the 2023 to 2024 hydrological year, equal to 1.2 millimeters of global sea level rise.
WMO noted that concentrations of carbon dioxide, methane, and nitrous oxide reached the highest levels ever measured in 2024. Initial readings for 2025 indicate that these levels are still rising.
CO2 has climbed from about 278 parts per million in the year 1750 to 423.9 parts per million in 2024. The increase from 2023 to 2024, at 3.5 parts per million, was the largest annual jump in recent observational history.
The agency linked these trends to extreme weather across many regions. Flooding, wildfires, extreme heat, and tropical cyclones caused major losses in 2025 and disrupted food systems and daily life. Many communities experienced displacement, adding pressure on development efforts.
Renewable energy systems were also affected. WMO reported that record heat in 2024 drove global energy demand to four percent above the long-term baseline, with some regions facing increases of nearly 30%. The update urges countries to integrate climate data into the planning and operation of renewable energy networks to ensure stable supply during periods of extreme heat and shifting weather patterns.
WMO said progress has been made in expanding early warning systems. Since 2015, the number of countries reporting multi-hazard early warning systems has more than doubled. Least developed countries and small island states reported further increases in coverage in the past year. Still, about 40 percent of countries lack such systems, leaving many communities exposed to climate-related hazards.
National meteorological and hydrological services now play a wider role in climate action plans. Nearly two-thirds provide essential or advanced climate services, compared with about one-third five years ago. These efforts support agriculture, water management, public health, and energy planning, but depend on sustained international support.
WMO presented the State of the Global Climate Update 2025 at COP30 in Brazil to provide negotiators with a scientific baseline.
The organization said the findings underline the urgency of limiting the scale and duration of any temperature overshoot and highlight the need for rapid action to reduce emissions and expand early warning systems.
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