A swath of the Midwest will get some relief from summer heat in the next three months, while the eastern and western thirds of the country can expect a hotter-than-normal season, forecasters said.

At the same time, La Niña conditions, which affect global weather patterns, including Atlantic hurricanes, may not develop until September or October, later than previously predicted, the National Oceanic and Atmospheric Administration's Climate Prediction Center said.

In the United States, temperatures are expected to top the 50-year historical average for most of the country from July through September. The Plains states, from Texas to the Dakotas, may see near-normal weather, the center said in its three-month outlook, released yesterday on the solstice, which is recognized as the first day of summer for the Northern Hemisphere. Southern California may also get near-normal temperatures due to cooler Pacific Ocean temperatures.

La Niña, which occurs when Pacific Ocean temperatures fall below the historical norm and could drive a more active Atlantic hurricane season, may not develop until late fall, later than forecasters previously expected.