Monsoons are long gone, but “Fall” temperatures are still cranking toward triple digits in Arizona this week.

The National Weather Service is closely following a La Nina system forming in the Pacific.

Looking at it as a game of probability, meteorologist Marvin Percha said, "The dice are loaded toward a little warmer and drier conditions in the Southwest this winter," while the Northern Rockies are likely to see ideal snow conditions.

“The odds favor, a bit, for them up there, versus further south or further east,” he said. 

East of the Northern Rockies, weather models are showing a bitter winter ahead and west of the mountain range milder, dryer conditions.

Percha said a La Nina develops when the central and eastern Pacific tropical waters cool, but it does not act alone, conditions in and around Alaska can shift jet streams and weather patterns.

Historically speaking, a weak La Nina favors the Rockies, “So, it should result in a little more snow than normal,” he said. “Maybe that might be a good place to look for a ski trip.”

Still, it is a game of chance, so the only thing he is willing to bet on is there won’t be rain for the next 10 days in Arizona.