The hurricane season is expected to be relatively quiet because of an El Niño weather pattern warming the central and eastern Pacific Ocean this summer or fall, researchers at the National Oceanic and Atmospheric Administration said Thursday.

In its annual forecast, NOAA said the Atlantic Ocean will swirl up eight to 13 tropical storms, three to six hurricanes, and one or two major hurricanes during the season that starts June 1 and ends Nov. 30.

A named storm has sustained winds of at least 39 mph. A hurricane has sustained winds of at least 74 mph. A major hurricane is a Category 3 or greater, meaning it has sustained winds of at least 111 mph. Any storm can have gusts that are more powerful than the sustained winds.

Based on the past 20 years, a typical hurricane season produces 12 named storms, including six hurricanes and two major hurricanes.

The lead hurricane forecaster at NOAA's Climate Prediction Center, Gerry Bell, said the Atlantic has experienced above-normal seasons for 12 of the past 20 years, but the heightened tropical activity is offset this year by El Niño, and by cooler Atlantic Ocean temperatures.

El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific that result in strong, upper-level westerly winds that break apart developing storms and hurricanes.

Bell said it is not clear what affect global warming will have on El Niño cycles that occur every three to six years. The last El Niño was in 2009.

El Niño lasts about one year and global warming is a much longer trend.

"In order to assess that issue, or to better understand it, we need climate models that handle both the global warming issue and El Niño. We're just not there yet," Bell said.

NOAA's hurricane forecast is the most closely watched forecast for the season. An earlier prediction in April by Colorado State University's Hurricane Forecast Team called for nine tropical storms, three hurricanes and one major hurricane.

Hurricane Gloria in September 1985 was the last time the eye of a hurricane made landfall in Connecticut. Hurricane Bob tracked through Rhode Island in August 1991. Tropical Storm Irene in August 2011 was downgraded from hurricane status by the time it swept through Connecticut. The core of Storm Sandy in October 2012 did not directly pass through Connecticut, though the rain, wind and storm surge ravaged the state.

Property-casualty insurers such as The Travelers Cos. and The Hartford Financial Services Group have a lot at stake during hurricane season because just one storm can cause billions of dollars in damage. For example, Hurricane Sandy in 2012 cost insurers $18.75 billion in claims, not including an additional $7.3 billion in flood claims paid by the National Flood Insurance Program, according to the Insurance Information Institute, a property-casualty research organization.

"Some of the costliest hurricanes in history have occurred in the past decade," the institute's spokesman, Michael Barry, said Thursday.

A year ago, NOAA's forecast in advance of the 2013 hurricane season called for 13 to 20 named storms, including seven to 11 hurricanes and three to six major hurricanes. The 2013 season actually brought 13 named storms, including two hurricanes: Humberto and Ingrid.

It was the sixth-least-active Atlantic hurricane season since 1950 "in terms of the collective strength and duration of named storms and hurricanes," according to NOAA.

A typical year has 12 named storms, though it also brings more hurricanes and major hurricanes, six and three, respectively. Last year was the third below-normal season since 1995, when the Atlantic basin began a period of greater storm activity.