Extratropical Highlights –November 2025

 

1. Northern Hemisphere

The 500-hPa circulation during November featured a canonical negative North Atlantic Oscillation (NAO) teleconnection pattern with enhanced above average height anomalies over Greenland and below average height anomalies stretching from eastern North America, across the North Atlantic Ocean, to Scandinavia (Figs. E7, E9). The main land-surface temperature signals include above average temperatures across most of North America and Eurasia (Fig. E1). The main precipitation signals include above average rainfall in northern Eurasia and below average rainfall in eastern North America and southern Eurasia (Fig. E3).

 

a. North America

The 500-hPa circulation during November featured an amplified ridge over the west half of Canada and the contiguous U.S., along with a strong maxima located over the Canadian Maritime. A strong center of below average heights was located over the Gulf of St. Lawrence and down the U.S. Eastern Seaboard and Midwest (Fig. E9). During the month of November, temperatures across North America were predominantly above average with large areas in the Western U.S. recording values in the highest 90th percentile of occurrences (Fig. E1). Precipitation totals were well below average across the eastern half of North America with several areas recording values in the driest 10th percentile (Fig. E3). Across the U.S., nearly all regions recorded below (or near normal) rainfall with the exception of Southern California which recorded above average rainfall due to a series of atmospheric rivers that impacted the region during November (Figs. E3, E5).

 

b. Europe and Asia

The 500-hPa circulation during November featured an amplified ridge over the Middle East and European Russia, and below average heights across the United Kingdom, Scandinavia, and Siberia (Fig. E9). Temperatures were largely above normal across Europe and Asia with several regions in the Middle East and European Russia recording values in the highest 90th percentile of occurrences (Fig. E1). Temperatures across Siberia and the Kamchatka Peninsula were below average or near normal (Fig. E1). Wetter than average conditions were recorded for the United Kingdom, northwest Spain, Southern Europe, and northern Russia, and drier than average conditions prevailed across the Middle East (Figs. E3, E4). Many areas in the European Plain received rainfall totals in the highest 90th percentile of occurrences (Fig. E3).

 

c. Atlantic hurricane season

The 2025 Atlantic hurricane season produced 13 named storms, with 5 becoming hurricanes and 4 of those becoming major hurricanes (average: 3). The 2025 Accumulated Cyclone Energy (ACE) value was about 7% above normal according to the 1951-2020 median. Based on this activity, NOAA classifies the season as being above normal based on ACE energy, despite the total number of storms being less than the average. An average season has 14 named storms, 7 hurricanes, and three major hurricanes. This season several storms reached Category 5 status, to include Erin, Humberto, and Melissa.

 

2. Southern Hemisphere

The 500-hPa height field during November resembled a quadrature wavetrain pattern with a maxima in heights located over Antarctica (Fig. E15). Temperatures were above normal or near normal across South America, Africa, and eastern Australia (Fig. E1). Below average rainfall was recorded across most of South America, including Brazil, which has recorded below average rainfall for the last year, and across central Africa (Figs. E3, E4). Above average rainfall was recorded across South Africa with several regions reaching the wettest 90th percentile of occurrences (Figs. E3, E4).

The Antarctic ozone hole typically develops during August and reaches peak size in September. The ozone hole then gradually decreases during October and November, and dissipates on average in early December. During 2025, the size of the ozone hole was well below the 2015-2024 range of ozone hole sizes and dissipated earlier than is typical (Fig. S6 top). The Southern Hemisphere vortex area also dissipated early and was below average, along with polar stratospheric cloud area, but within the 2015-2024 range of measurements (Fig. S6 middle and bottom).