Reno, with 14 100-degree days, sees hottest July on record

RENO — July was the hottest month in Reno in 125 years of record-keeping, the National Weather Service said Wednesday.

The mean average temperature for July was 81.8 degrees at Reno-Tahoe International Airport — 6.9 degrees above normal and 1.3 degrees higher than the second warmest July on record. That was last summer.

Reno also tied the warmest overnight low of 77 degrees for July on Monday, the weather service said.

There were 14 days last month when the high reached 100 degrees. That’s four more than any previous month and just three shy of the most 100-degree days in a year, the service said.

Climatological data for Reno dates to 1893.

The record heat is part of a big shift that started emerging in about 2000, said Dan McEvoy, assistant research professor of climatology at the Western Regional Climate Center in Reno.

“We can conclude that it is substantially different than the earlier decades,” he told the Reno Gazette Journal . “What the climate projections showed 10 to 15 years ago is happening and we expect that to continue.”

Reno’s high has hit triple-digits seven of the past eight days and 12 of the last 17. The daily high never dipped below 90 last month, something that’s only happened once before — also July 2017, the weather service said.

“We are seeing this year after year now, where the next year is the hottest year,” McEvoy said. “I’m a little concerned about that phrase ‘the new normal’ because in 10 to 15 years it will be different.”

Noah Diffenbaugh, a professor of earth system science at the Stanford Woods Institute for the Environment at Stanford University, said the change in temperature provides the clearest picture of global warming. “When we look across the globe, we find a fingerprint of global warming for the record hottest temperature in more than 80 percent of the world,” he told the Gazette Journal.

Although some amount of future warming is already baked into the earth’s climate because of past fossil fuel use, there’s still an opportunity to reduce it by reducing the output of greenhouse gases, the fossil fuel byproducts that trap atmospheric heat and cause global warming, Diffenbaugh said.

“As long as we continue to emit greenhouse gases into the atmosphere, we can expect additional global warming,” he said.