Continuing a string of global heat records, last month was the hottest July ever recorded, NASA said. But the agency added a wrinkle: Because July is always the hottest month of the year, this July was the hottest of any month since adequate record-keeping began in 1880.

The recent El Niño contributed to the record, as did overall warming linked to greenhouse gas emissions. El Niño, in which sea surface temperatures rise in the eastern Pacific, has now ended. One question for forecasters is whether there will be a transition to La Niña conditions, in which sea surface temperatures fall below normal. If that happens, while next year may still be hot, temperatures may stay below this year’s records.