The conditions led to a worsening drought in parts of the United States, particularly the Southwest and many cities along the Eastern seaboard, the National Climatic Data Center reported.
Overall it was the ninth warmest April on record for the United States at an average of 54.6 degrees Fahrenheit in the 48 contiguous states. That is 2.6 degrees above the 1895-2002 long-term average.
Worldwide, preliminary data show the average land and ocean temperature in April was 56.7 degrees Fahrenheit, 1.03 degrees above the long-term average.
That's the second warmest average since 1880. The warmest April worldwide was in 1998, when a strong El Nino warming of the equatorial Pacific Ocean helped raise the readings. Researchers report that another El Nino is developing, with sea-surface temperatures rising above their usual levels in the Pacific.
The Center reported that severe drought affected about 21 percent of the contiguous United States as of the end of April. That was down from 36 percent last August.
There are long-term water deficits in much of the West, with the biggest problems from the northern and central Rockies to the Southwest.
The agency said that while a series of storms brought some improvement in drought conditions from northern Virginia to Maine, the persistence of severe to extreme drought required the continuation of drought emergencies in many cities along the northeastern seaboard.
Rainfall was below to much-below average across most southern states. Conditions steadily worsened throughout a large part of the Southwest following a winter of very low snowfall.
The report said that by the end of April extreme drought covered a large part of the West from Montana to New Mexico and Arizona. Montana has experienced some of the most severe drought conditions in the nation.
"The past seven months have been the driest October through April on record in Colorado," the report added, leading to numerous wildfires and concern that the 2002 wildfire season may be extremely busy.
For much of the nation April began with cooler than normal temperatures, followed by record highs in many cities from the Plains to the East Coast.
Overall, temperatures were above average in states from Arizona to Florida and along the eastern seaboard as far north as Connecticut and Rhode Island. It was the warmest April on record in North Carolina, South Carolina and New Mexico and the third warmest April in Florida, New Jersey and Rhode Island.
In other countries in April:
The National Climatic Data Center in Asheville, N.C., is part of the Commerce Department's National Oceanic and Atmospheric Administration.