Hurricane season has officially begun, and forecasters expect the Atlantic Ocean will spawn a near-average number of such storms in 2016.

“sound relaxed and encouraging, but we could be in for more activity than we’ve seen in recent years,” warned Kathryn Sullivan, head of the National Oceanic and Atmospheric Administration (NOAA), which issues forecasts every year.

The past three years have seen a hurricane drought in the Atlantic. There were only four hurricanes and seven tropical storms in 2015. A typical season, which runs from June 1 to Nov. 30, sees six hurricanes.

Tropical Storm Bonnie makes landfall in South Carolina on May 28. (NASA Image/AFP/Getty Images)

The 2016 NOAA forecast calls for a total of 10 to 16 named storms, including both tropical storms and hurricanes. This year’s Hurricane Alex, rare because it formed in January, counts as the first. Tropical Storm Bonnie, which made landfall in South Carolina on May 28, is the year’s second named storm.

The forecast predicts that four to eight named storms may become hurricanes — organized, rotating storms with sustained winds of 74 mph or faster. Between one and four could become major hurricanes, with winds of at least 111 mph.

Two big climate influences could affect the number and strength of expected storms: the Pacific Ocean’s El Niño/La Niña cycle and the Atlantic Multidecadal Oscillation (AMO). Both are natural climate patterns that influence ocean surface temperatures and wind patterns, two critical ingredients in creating hurricanes.

An active El Niño favors more hurricanes in the eastern Pacific and fewer storms in the Atlantic, Sullivan said. According to NOAA, the 2015-2016 El Niño is fading, and the pattern may flip over to its cooler La Niña phase sometime after August, when hurricane season peaks. La Niña favors a more active Atlantic hurricane season.

The AMO, which flips back and forth every 25 to 40 years, also shows hints of switching to a cool phase, Sullivan said. When the AMO is in a cool phase, the Atlantic generally sees fewer hurricanes. “If this shift proves to be more than short-lived, and not just a temporary blip, then it could signal the arrival of lower activity” in the Atlantic, Sullivan said.

The seasonal forecasts do not offer predictions about whether any storms will make landfall in the United States. Weather patterns in place when a hurricane approaches have a major effect on a storm’s path, which makes it hard to predict landfall more than a few days in advance.