September 2025 has been marked as the third-warmest September on record, according to data from the European Copernicus Climate Change Service cited on October 9. This assessment is corroborated by the Japan Meteorological Agency, which also noted that this September trailed only the warm months of September in 2023 and 2024. While the label “third warmest” may not seem overly alarming, it follows two remarkably hot years bolstered by a significant El Niño phenomenon superimposed upon the enduring effects of human-induced climate change. Notably, September 2025 was warmer than any September prior to 2023, regardless of the presence of El Niño or La Niña conditions, as emphasized by weather records expert Maximiliano Herrera.
However, the ongoing U.S. government shutdown means that data updates from NOAA and NASA are likely to be delayed beyond their anticipated release date of October 10.
In the context of precipitation, the contiguous United States experienced one of its driest Septembers in nearly six decades, ranking as the third driest, according to climatologist insights. The impact of climate change varies greatly, with land areas warming approximately 40% faster than the global average, particularly in high-latitude regions.
Additionally, September 2025 saw a shift towards La Niña conditions, as reported by NOAA. This transition in the El Niño/Southern Oscillation (ENSO) suggests that La Niña may persist through early 2026, with a 78% likelihood of continuation over the October-December period. The long-term forecasts indicate that conditions favorable for another El Niño event may develop later in 2026, perpetuating the cycle of extreme temperatures and climatic effects.
Arctic and Antarctic regions have also exhibited concerning trends. September 2025 recorded the 11th-lowest extent of Arctic sea ice since satellite monitoring began, with a significant deficit compared to historical averages. This trend also extends to the Antarctic, where September 2025’s sea ice extent was the third lowest in recorded history.
In terms of extreme weather, the month was marked by numerous heat records worldwide, with significant highs noted such as 49.8°C (121.6°F) in Iran and 43.4°C (110.1°F) in Paraguay. Notably, four all-time heat records were documented in various global stations throughout September, reinforcing the notion of escalating temperatures associated with climate change.
This evident warming trend emphasizes the urgent need for climate action and adaptation strategies. While these findings reflect ongoing challenges, they also highlight opportunities to engage in meaningful discussions about climate resilience, mitigation efforts, and embracing sustainable practices in line with the realities of a warming planet. Addressing these phenomena collaboratively could steer us towards a more hopeful and sustainable future.