This month is likely to be Phoenix’s hottest December on record. The previous record was set just last year.
As of Wednesday, this month’s average temperature has been 62.9 degrees, which is nearly 7 degrees hotter than normal for December. Last December’s average temperature was 62.3 degrees.
Five days this month have broken daily heat records with highs in the 80s.
The warm winter weather is partly a result of La Niña conditions in the Pacific.
“[La Niña is] a cooling of the central Pacific Ocean. And since the Pacific Ocean is so big, when you cool down a part of it, it changes the weather patterns across the world, particularly across the United States,” said Randy Cerveny, professor of geographical sciences at ASU.
But, Cerveny told KJZZ’s The Show, climate change makes the impact more extreme.
“Under normal circumstances, when we have this kind of a big ‘ridge’ over top of the Western United States, we would have good, warm temperatures. But the fact that they are setting records is part of the underlying climate change.” Cerveny said.
The climate research organization Climate Central ranks Phoenix’s temperatures for the last few days in the “extreme” category of its Climate Shift Index scale — the second-highest ranking in the scale.
That means the kinds of temperatures Phoenix has had this week are at least four times more likely as a result of human-caused climate change, and conditions like this would have been very unlikely in pre-industrial times.
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