Assessing the U.S. and Global Climate in September 2024

Second-warmest September on record for the U.S. and Globe; Hurricane Helene caused widespread power outages and catastrophic flash flooding across the Southeast U.S., causing at least 200 fatalities

A rain-swollen Reems Creek in Weaverville, NC in the aftermath of Hurricane Helene. The remnants of a red water wheel and other debris lie along the side of the falls.

Courtesy of Sara Veasey, NOAA NCEI

September Highlights:

The release of the September 2024 U.S. and Global Climate Reports was delayed due to significant infrastructure damage near NOAA National Centers for Environmental Information (NCEI) headquarters in Asheville, NC from Hurricane Helene. NCEI is in the process of returning to full operations and anticipates restoration of most data feeds in the near future.

Temperatures were above average across much of North and South America as well as Europe, but globally, temperatures averaged cooler than what was observed during September 2023, ending the 15-month record streak of record warm global temperatures.
The year-to-date global temperature was the warmest such period on record, with North America, South America, Europe, and Africa each ranking first.
The contiguous U.S. was second warmest on record with record warm conditions blanketing portions of the northern Plains, Upper Midwest, and south Florida.
Year-to-date temperatures across the contiguous U.S. averaged second warmest on record.
Hurricane Helene was the strongest hurricane on record to strike the Big Bend region of Florida, the deadliest Atlantic hurricane since Maria (2017), and the deadliest to strike the U.S. mainland since Katrina (2005).
Three new hurricanes (Debby, Helene, and Milton) and one tornado outbreak were added to the 2024 Billion Dollar Weather and Climate Disaster total. The year-to-date total now stands at 24 events — the second-highest event total for this period.

Temperature

The September global surface temperature was 2.23°F (1.24°C) above the 20th-century average of 59.0°F (15.0°C), making it the second warmest September on record. This value was 0.34°F (0.19°C) cooler than what was observed during September 2023. According to NCEI’s Global Annual Temperature Outlook, there is a 99.8% chance that 2024 will rank as the warmest year on record.

Global map of Surface Temperature Departure from the 1991–2020 Average for September 2024 (°C) with warmer areas in gradients of red and cooler areas in gradients of blue.

The average temperature of the contiguous U.S. in September was 68.6°F, 3.8°F above average, ranking second warmest in the 130-year record. Generally, September temperatures were above average across much of the contiguous U.S., with near average temperatures observed from portions of central Texas to the central Atlantic Coast. Arizona, Wyoming, North Dakota, South Dakota, and Minnesota each ranked warmest on record for September.

Map of the U.S. showing temperature departures from average for September 2024 with warmer areas in gradients of red and cooler areas in gradients of blue.

Other Highlights

Arctic sea ice extent was the sixth smallest in the 46-year record at 1.69 million square miles. Antarctic sea ice extent was 6.59 million square miles, the second lowest on record.
The Northern Hemisphere snow cover extent in September was slightly below average. Snow cover over North America was below average (by 320,000 square miles); Eurasia was slightly above average (by 90,000 square miles).
Global Precipitation in September was near the long-term average. Notably, much of the Sahara desert had its wettest September on record, driven by the rare passage of an extratropical cyclone on September 7-8.
The U.S. has sustained 400 separate weather and climate disasters since 1980 where overall damages/costs reached or exceeded $1 billion (including CPI adjustment to 2024). The total cost of these 400 events exceeds $2.785 trillion.
- Cost estimates for Hurricanes Helene and Milton have yet to be determined and are not part of the cost total at this time.
- The 2024 Billion Dollar Weather and Climate Event Disaster total of 24 events through mid-October is second only to the 27 events reported by this time last year.

U.S. map showing locations of billion dollar disasters in 2024 through the middle of October with icons and text describing each event.
This monthly summary from NOAA’s National Centers for Environmental Information is part of the suite of climate services NOAA provides to government, business, academia and the public to support informed decision-making. For additional information on the statistics provided here, visit the Climate at a Glance and National Maps webpages. For a more complete summary of global climate conditions and events, explore our Climate at a Glance Global Time Series.