Global ocean surface temperatures set a record for the fourth consecutive month in September, and North America had its warmest September on record, according to NOAA's National Centers for Environmental Information. The ocean departure of 1.98 degrees Fahrenheit (1.10 degrees Celsius) above the September average was the highest for any month in NOAA's record, edging past August 2026 by 0.04°F, according to the agency's global climate report released Oct. 9.

The contiguous United States set its own record. September averaged 69.4°F, 4.6°F above the 20th-century average and the warmest September in 132 years of records, beating the previous high of 68.95°F set in 1998, NOAA's national climate report said.

The records matter for household costs and safety. Unusual September heat extends air-conditioning season and electricity bills, stresses outdoor workers and crops — and warm oceans can help fuel stronger storms and heavier rain.

A Global Record Run Led by the Oceans

The planet as a whole came close to its record. NOAA said September's global surface temperature was 2.39°F (1.33°C) above the 20th-century average, "the second-warmest September in the 1850–2026 record," behind only 2023. It was the 51st consecutive September above the 20th-century average, and all 10 warmest Septembers have occurred since 2015.

Land areas ran 3.29°F (1.83°C) above average, the third-warmest September on record. Temperatures more than 3.6°F (2.0°C) above average covered much of North America, parts of Europe, western Asia, Australia and western Antarctica. NOAA found no regions with record-cold September temperatures on land or at sea.

Asia and the Arctic also had their warmest Septembers on record, while Antarctica was near average. For January through September, the globe ranked second warmest, behind 2024, and NOAA said 2026 is very likely to rank among the five warmest years, with the highest odds favoring second place.

El Niño Adds Heat to an Already Warm Ocean

NOAA attributed record warmth across the central and eastern tropical Pacific to persistent El Niño conditions. The El Niño, now among the strongest observed, warms large areas of the Pacific surface and typically pushes global temperatures higher in the months that follow.

El Niño is not the whole story — the ocean was already warm. Ocean temperatures have been running at or near records for much of the past several years. Single months cannot be attributed to any one cause without formal analysis, but the long-term warming of the oceans is well documented.

The warm water had visible effects. NOAA said the eastern North Pacific set September records for hurricanes, with seven, and major hurricanes, with five, and that Hurricane Polo ranked as the second-most intense hurricane on record in that basin by pressure. In the Atlantic, no hurricane formed before October for the first time in the satellite era.

U.S. Heat and Drought by Region

The U.S. record was broad. Eight states had their warmest September on record, and Arkansas, Illinois, Kansas, Missouri and Oklahoma broke records dating to the 1920s or 1930s, according to NOAA.

Heat combined with dryness in much of the country. About 59% of the contiguous U.S. was in drought on the Sept. 29 U.S. Drought Monitor, roughly the same as at the start of the month. In the South, 89% of the region was in drought, its largest extent since October 2000.

Precipitation nationally was near normal at 2.69 inches, slightly above average, but that rain fell unevenly. The weekly U.S. Drought Monitor map, released each Thursday, is the best way for residents to check conditions in their own county, because national averages can hide sharp local differences.

The numbers NOAA reports are departures from a long-term baseline, in this case the 20th-century average, rather than raw temperatures. A departure of 4.6°F across the entire contiguous U.S. for a full month is large, because it averages together hot and cooler places and days. That is why a national monthly record is harder to set than a record high at a single weather station, and why breaking a 1998 record by nearly half a degree stands out in the 132-year record. For farmers and ranchers in drought areas, a hot September worsens stress on pastures, stock ponds and late-season crops, and for cities it can mean higher water demand.

Households in the hardest-hit regions can watch for local water-use advisories, check on older neighbors during late-season heat, and look for utility bill assistance programs if cooling costs rise. Farmers in drought-designated counties may qualify for U.S. Department of Agriculture disaster programs.

Ice, Storms and the Months Ahead

Global sea ice also shrank. NOAA said global sea ice extent in September was the third smallest in its 48-year record, at 8.54 million square miles, with Antarctic extent also third smallest. Arctic sea ice ranked 13th lowest for September.

Several questions remain open, including how high the El Niño peaks this winter and whether 2026 ends as the second-warmest year. Those outcomes depend on the coming months, and forecasts are probabilistic.

NOAA releases its October global and U.S. climate reports in early November. Nature World News will report on whether the ocean record streak continues.

The bottom line is that the oceans have now set four monthly heat records in a row, and Americans just lived through the warmest September in the national record. Residents in drought and heat-prone regions should prepare for continued water and energy strain, and follow local forecasts as El Niño shapes the winter.

What Readers Want to Know

What record did the oceans set?

Global ocean surface temperatures were 1.98°F above the September average, the highest departure for any month in NOAA's record and the fourth straight monthly record.

Was September the hottest on record globally?

No. NOAA ranked it the second-warmest September since 1850, behind 2023.

How hot was September in the U.S.?

The contiguous U.S. averaged 69.4°F, 4.6°F above average, the warmest September in records dating to 1895.

Which states set records?

Eight states had their warmest September on record, including Arkansas, Illinois, Kansas, Missouri and Oklahoma.

Is El Niño responsible?

NOAA said persistent El Niño conditions drove record warmth in the tropical Pacific. Long-term ocean warming also contributes, and single months are not attributed to one cause without formal study.

When is the next NOAA climate report?

NOAA publishes its October global and U.S. climate reports in early November.