The National Oceanic and Atmospheric Administration (NOAA) announced today that the lower 48 U.S. states recently experienced their warmest May on record.

Records have now been kept for 124 years.

"Last month, the U.S. sizzled with record warmth," the government agency said in a statement. NOAA reports that temperature records in more than 8,590 locations were broken, or tied, in May 2018.

The May record, which is more than 5 degrees above average, is part of Earth's continuing warming trend, something NASA scientists say has been particularly rapid in the last 40 years.

A total of eight U.S. states broke their temperature records this May, said NOAA, and another 34 states experienced above-average-heat.

"The fact is the planet is warming and that is increasingly evident at the local and regional level," Gavin Schmidt, the director of NASA'sGoddard Institute for Space Studies, said via email.

"The key take home message is that the long term trends are clear," said Schmidt. "Global and regional warming is happening now."

Although we're not even halfway through 2018, the year will likely fall into the top five of the warmest years on record globally, said Schmidt.

Previously, both NASA and NOAA concluded that 2016 was the warmest year on record, and 2017 since took second place.

We will continue to break records, both regionally (like in the U.S), and globally, said Schmidt. But both he and other scientists emphasized that longer-term trends remain the more important figures.

"I think it’s significant in the sense that with long term trends, you’re more likely to see record highs (and much less likely to see record lows), so this certainly fits that pattern," Walt Meier, a senior research scientist at the National Snow and Ice Data Center, said via email.

These monthly figures, though, can't be relied upon to tell the whole story. Weather will always be quite variable, so "it’s still certainly possible to have relatively cool months even during an overall warming trend," said Meier.

"It’s not the best indicator of long-term global warming trends," Meier added.

"One hot May, even the hottest May on record, is not itself hugely significant," Sarah Green, an environmental chemist at Michigan Technological University, said via email.

"What's alarming is the continuous month-by-month, year-by-year increase that has been measured over the past 30 years."