September 2025 ranked as Earth’s third warmest September in recorded history
September 2025 has been identified as the third warmest September in Earth’s recorded history. This finding comes from the European Copernicus Climate Change Service and the Japan Meteorological Agency. Both agencies agree that September 2025 trails only behind those in 2023 and 2024 for record warmth, with data comparisons dating back to 1850.
Climate Trends and Impacts
The persistent warmth over recent years continues to be influenced by a strong El Niño event, alongside ongoing human-induced climate change. According to climate expert Maximiliano Herrera, September 2025 was warmer than any September in the records before 2023, regardless of whether El Niño or La Niña conditions were present.
ENSO Developments
Currently, La Niña conditions persist as reported by NOAA’s October discussion. This pattern shift suggests a cooling effect on the Pacific Ocean, with predictions that these conditions will linger through early 2026. The chance of La Niña continuing into February 2026 stands at 78%, according to NOAA forecasts. A return to ENSO-neutral conditions is anticipated around March 2026, with potential signs of another El Niño event later in 2026.
Arctic and Antarctic Sea Ice Observations
- Arctic Sea Ice: The September 2025 extent was the 11th lowest on record, measuring 1,660,000 km² below the 1981-2010 average, as per the National Snow and Ice Data Center.
- Antarctic Sea Ice: Ranked third lowest for September, behind 2023 and 2024. Its annual maximum, recorded on September 17, was among the smallest since the introduction of satellite records.
Temperature Extremes and Records
Significant temperature extremes characterized September 2025 globally. The hottest recorded temperature in the Northern Hemisphere reached 49.8°C in Shabankareh, Iran, on September 10. Meanwhile, the Southern Hemisphere’s highest temperature hit 43.4°C in Base Jara, Paraguay, on September 14.
Record-Breaking Temperatures
Several global weather stations with long-standing records experienced unprecedented heat:
- Sendai, Japan: 37.4°C on September 2
- Roosevelt Airport, St. Eustatius: 34.4°C (new record high) on September 13
Notable Heat Records
| Location | Temperature (°C) | Date |
|---|---|---|
| Lhokseumawe, Indonesia | 36.9 | September 1 |
| Sendai, Japan | 37.4 | September 2 |
| Watari, Japan | 36.1 | September 2 |
| Roosevelt Airport, St. Eustatius | 34.4 | September 13 |
In addition, 59 other locations globally have set or tied monthly heat records, illustrating the widespread effects of current climate trends. The global communities remain vigilant as these temperatures indicate the larger impacts of climate change, crucial for shaping future climate policies.
