La Niña and hurricanes

As of the middle of August, there have been five named storms in the Atlantic and Caribbean waters. This number is close to normal for this time of year, but we’re approaching the peak of the tropical storm and hurricane season. Historically, the most active period is late August into September, with the peak around Sept. 10.

The fifth named storm of the season, Erin, rapidly intensified over the weekend into a strong Category 5 hurricane before being downgraded. The storm was not expected to directly hit the eastern coastline of the U.S., but heavy rains were likely in the Caribbean Islands and large swells around other islands and the East Coast. Hurricane Erin was also one of the fastest-intensifying hurricanes in history, especially in August.

Since last year, we’ve been in a “La Nada,” the in-between warmer El Niño and cooler La Niña sea-surface temperature event. According to the Climate Prediction Center, there is a 56% chance that conditions will remain “neutral” into October. However, forecasters are indicating that we could have a weak and brief La Niña late this year and into early 2026 based on some computer model projections. There are other forecast models of sea-surface temperatures that show the La Nada continuing into the winter season.

Despite the potential upcoming change in sea-surface temperatures, NOAA’s National Weather Service is still expecting about 13 to 18 named storms for the 2025 tropical storm and hurricane season. Forecasters also predict five to nine hurricanes, with the potential of two to five hurricanes becoming major, which is a Category 3 or higher with winds of at least 111 miles per hour. The National Weather Service has the odds at 50% of an above-normal season of named storms, with a 35% chance of a near-normal season.

One of the reasons why the tropical storm and hurricane season forecasts are above normal once again is the warmer-than-average sea-surface temperatures in the Atlantic and Caribbean waters. The latest information has ocean waters at least several degrees above normal levels. For tropical storms and hurricanes to form in these regions, ocean temperatures need to be at least 80 degrees Fahrenheit. During the summer seasons of the last several years, average sea-surface temperatures in the Atlantic and Caribbean, as well as the Gulf of Mexico, have been at record levels.

Based on the 30-year average from 1991 to 2020, the number of named storms is 14, with seven of them becoming hurricanes. There is also an average of 3 major hurricanes. The Atlantic tropical storm and hurricane season officially began June 1 and continues through Nov. 30.

Since the 1980s, the sea-surface temperatures in the Caribbean region have been showing an overall trend of warming. There have been some variations with more warming in particular areas.

Since 2016, the number of named storms in the Atlantic and Caribbean has been at or above the normal of 14. The highest number, which occurred in 2020, was 30. During that year, there were also 14 hurricanes and seven of them were major.

The 2024 Atlantic and Caribbean season was one of the most active ones in recorded history. Last year’s season had 18 named storms and 11 hurricanes. Five of the storms were at least a Category 3. It was also the third-costliest hurricane season in history, with total damage at slightly more than $130 billion. The 2005 season was by far the costliest. Hurricane Katrina alone had damage of around $125 billion, with over $171 billion for the season.

The strongest hurricane last year was Milton with 180 miles per hour maximum sustained winds. That storm experienced very rapid intensification, and it was the fourth most intense hurricane in the Atlantic on record and the strongest ever recorded in the Gulf of Mexico.

In terms of our local weather, it’s sounding like a broken record, but conditions continue to remain much drier than normal across the Inland Northwest. The rain showers over the weekend did push our August precipitation total to 0.25 inches. The normal moisture for Coeur d’Alene this month is 1.23 inches. At the Spokane International Airport, only 0.06 inches has been measured this month.

The long-range computer models are still indicating a below-normal moisture pattern through at least the end of the month. There is a chance we could see some showers or a thunderstorm around the 22nd of the month, which is the new moon lunar phase.

Eventually, this dry pattern is expected to shift to the much wetter side, but that may not occur until the early fall season. With the possibility of a new La Niña developing by the end of the year, the chances for increased snowfall across the region are higher. For the 2024-25 season, only 36.1 inches of snow fell at Cliff’s station. We do believe that amounts will be a little higher for the 2025-26 season. We’ll have more details later in the year.

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Contact Randy Mann at [email protected].