The proportion of days in the United States that are warmer than the long-term average increased from 42 percent in 1964 to 67 percent today, according to an analysis of 3.2 million temperature anomalies over the last 50 years.
Enigma.io, a New York City-based company that specializes in searches of information from public databases, examined data from 2,716 U.S. weather stations to track the temperature anomalies. The company found that since 1964, temperature anomalies characterized as warm or “strong warm” have increased by an average of .5 percent a year.
Enigma’s data show, for example, that in 2012, 84 percent of temperature anomalies in the U.S. skewed on the warm side. The company forecast that by the 2030s more than 70 percent of anomalous temperatures in the U.S. are likely to be higher than the historical average, rather than colder.