October turns on America’s burners — and turns off the taps » Yale Climate Connection

The U.S. National Oceanic and Atmospheric Administration (NOAA) reported on Friday that the continental United States had its second driest month on official records since 1895, after two hurricanes caused catastrophic flooding. The average precipitation for October in the lower 48 states was 0.95 inches, tying October 1963 and November 1917 as the second driest month on record in the 130-year history of records. October 1952 was much thicker than the other months, with only 0.54 inches recorded. (For more information about that month and the related 1950s drought, see our October 25 post.)

As October approaches, drought and drought conditions are noticeably intensifying across the United States. As of November 5 (based on data through November 3), the U.S. Drought Monitor shows that 87.78% of the contiguous United States is experiencing abnormal drought or drought. This is the highest weekly percentage in the 25-year history of the Drought Monitor (previous record: 85.28% on November 1, 2022) and a significant increase from the 70.65% drought coverage reported on October 1. , may reduce this percentage. According to Gallagher Re, as of September 2024, drought in the United States has caused more than $2 billion in losses during the year. These damage totals will undoubtedly rise.

Like most calendar months of the year, October has become progressively wetter on average nationwide, with precipitation increasing by approximately 15% since the 1890s (see Figure 1). But this does not mean that the moisture distribution is good. Human-caused warming is leading to a well-documented trend of “concentrated”, more intense rainfall extremes interspersed with hotter, more impactful drought periods. More variation means it's harder to adapt to extremes in either direction.

Of particular interest are some local records. Several major East Coast cities with more than a century of climate data experienced their driest months on record. Here are some of the places where October had its driest month on record, along with the Period of Record (POR), compiled by weather historian Christopher Burt. A value of 0.00 inches means that not even a trace of precipitation (not a single raindrop or snowflake) was measured.

• New York City, NY (Central Park): .01 inch (old model 0.02 inch in June 1949); Bohr 1869-
• Newark, New Jersey:Trace (0.07 inches old in June 1949); POR 1931- in the NOAA NOWData online database, but the actual POR is 1843-. The driest month between 1843 and 1931 was September 1884, with a thickness of 0.25 inches.
• Philadelphia, Pennsylvania:Trace (old 0.09 inches between October 1924 and October 1963); Bohr 1871-
• Allentown, Pennsylvania: 0.02 inches (old 0.09 inches in May 1964); Bohr 1912-
• Trenton, New Jersey:Trace (old 0.05 inches in October 1963); Bohr 1865-
• wilmington, delaware:Trace (old 0.05 inch in October 1924); Bohr 1894-
• Salisbury, MD:0.01 inch (0.09 inch as of November 2001); 1906-
• Atlanta:Trace (associated with October 1963); Boer 1878-
• Macon, Georgia:0.00 inch (as of October 1963); Bohr 1892-

Among the 48 contiguous states, 21 experienced their driest conditions in October. This was the driest October on record in New Jersey and Delaware, and the second driest in seven other states (see Figure 2). Only Florida received above-average rainfall, mostly due to Hurricane Milton.

The warmest fall in U.S. history so far

According to NOAA, the continental United States experienced its second-warmest October in 130 years, tying it with 1947 and not reaching the warmest October until 1963. Three large states—Arizona, New Mexico, Texas, and Utah—had their hottest October on record, as shown in Figure 3.

Even more noteworthy, the fall of 2024 (September-October) is by far the warmest in the history of the contiguous United States, almost a full degree Fahrenheit warmer than September-October 2015 (63.79°F vs. 62.87 °F). This gap is much larger than the gap between any other two September-October periods in the 130-year database.

Year-to-date, it is the second-warmest January to October on record, behind only 2012. By October, another 35 states had experienced their hottest January to October on record.

Temperatures were above average during the first week of November as very mild weather in the central and eastern United States outweighed cold weather in the West. This pattern is expected to continue for much of the next two weeks.

Jeff Masters contributed to this article.