A recordkeeping change has altered expectations for the number of tropical storms in an Atlantic hurricane season. The average number of named tropical storms in a year is now 14, up from an average of 12 before the change, the National Oceanic and Atmospheric Administration said. The numbers are based on a 30-year period, NPR reports, and the agency shifted to a new time frame on Friday, effective this season—1991 to 2020 instead of 1981 to 2010. The average for hurricanes is seven, up from six. The average number of Category 3, 4 or 5 hurricanes stays at three, per Axios. The agency made no adjustments for the Pacific Ocean. "These updated averages better reflect our collective experience of the past 10 years, which included some very active hurricane seasons," said a forecaster for the agency.
At the same time, with average temperatures rising in the US and precipitation becoming more erratic in places, the agency is adjusting what's considered normal weather. As of next month, NOAA will use the higher temperature baseline of the past 30 years to reflect "normal." Climate change hasn't been shown to affect the total number of storms, but hotter water near the ocean surface can bring hurricanes that are more powerful. That's been the case in the Gulf of Mexico lately. "NOAA scientists have evaluated the impacts of climate change on tropical cyclones," the forecaster said, "and determined that it can influence storm intensity." Storms also are being spotted sooner because of improved technology. On Friday, President Biden proposed a $1.4 billion increase in the agency's budget, up from the current $6.9 billion. (Read more tropical storms stories.)