WASHINGTON (AP) — The jet stream, the river of air high above Earth that generally dictates the weather, usually rushes rapidly from west to east in a mostly straight direction.

But lately it seems to be wobbling and weaving like a drunken driver, wreaking havoc as it goes.

The more the jet stream undulates north and south, the more changeable and extreme the weather.

The most recent example occurred in mid-June when some towns in Alaska hit record highs. McGrath, Alaska, recorded an all-time high of 94 degrees on June 17. A few weeks earlier, the same spot was 15 degrees, the coldest recorded for so late in the year.

You can blame the heat wave on a large northward bulge in the jet stream, Rutgers University climate scientist Jennifer Francis said.

Several scientists are blaming weather whiplash — both high and low extremes — on a jet stream that’s not quite playing by its old rules. It’s a relatively new phenomenon that experts are still trying to understand.

Some say it’s related to global warming, but others say it’s not.

Upside-down weather also happened in May: Early California wildfires fueled by heat contrasted with more than a foot of snow in Minnesota. Seattle was the hottest spot in the nation one day, and Maine and Edmonton, Canada, were warmer than Miami and Phoenix.

Consider these unusual occurrences over the past few years:

— The winter of 2011-12 seemed to disappear, with little snow and record warmth in March. That was followed by the winter of 2012-13 when nor’easters seemed to queue up to strike the same coastal areas repeatedly.

— Superstorm Sandy took an odd left turn in October from the Atlantic straight into New Jersey, something that happens once every 700 years or so.

— One 12-month period had a record number of tornadoes. That was followed by 12 months that set a record for lack of tornadoes.