July in the U.S. was the hottest month ever in records going back to 1895. And the 12-month period ending in July also was the warmest. Read a New York Times article on the records and the causes. According to scientists quoted by the Times, the drought afflicting most of the country reduced soil moisture, leading to higher daytime temperatures in July. The higher nighttime lows most of the country experienced are part of a long-term trend.