It's been an unusual start to November, and the reason may surprise you.

Blooming flower buds next to trees with changing leaves. Fans and air conditioners working overtime. Iced coffees instead of hot ones. Temperatures more like Florida than the Mid-Atlantic. The weather has been weirdly warm in the eastern two-thirds of the United States as November gets started -- more than 10 degrees above average across parts of over 20 states.

Conditions in the Rockies and on the West Coast have balanced out some of the unusual eastern warmth, with cooler-than-average temperatures and a big early-season dump of snow.

But in the eastern half of the nation, will you eventually be able to pull out your hats and gloves this coming winter? Or is the subtropical weather here to stay?

The answer can be partially found some 5,000 miles away in the North Pacific Ocean, where the jet stream has been blowing more strongly than it normally does from north of its typical position.

The jet stream is a fast-flowing ribbon of air in the upper atmosphere that carries storm systems from west to east. The positioning of the jet stream is influenced by differences in temperature, called gradients.

A marine heat wave, or an expansive region of highly unusual warm sea temperatures, is sprawled out across the North Pacific to the east of Japan, extending for thousands of miles.

This feature has been associated with a North Pacific jet stream anomaly, allowing it to blow strongly into Alaska and western North America.

The jet stream's predicted strength and trajectory is shown in the animation below.

Air masses that have been transported by the strong jet stream have delivered relatively cooler conditions to Alaska and parts of western North America, but much milder conditions to the east.

As the air masses cross the Rocky Mountains, associated air parcels warm up and dry as they move into areas with lower elevations -- otherwise known as a downsloping wind, whereby the warming is driven by increasing atmospheric pressure. They are also sometimes called Chinook winds.

It's this pattern that has been common throughout meteorological fall, which started Sept. 1 in the Northern Hemisphere, allowing cooler air masses to only briefly affect much of the central and eastern United States. A La Niña-like pattern, associated with cooler-than-average seas in the equatorial Pacific, has also been a contributing factor.

And it's set to continue through mid-November, with several additional surges of mild, Pacific air across North America, with a few cooler exceptions.

This warmer-than-average pattern will probably come with a few more opportunities for highs in the 60s and 70s from the Plains to the Midwest and the Mid-Atlantic states when highs would more typically be in the 40s and 50s this time of year.

The southern tier of states will continue to bask in 70 and 80 degree warmth.

However, the Great Lakes, Northeast and New England will be a cooler exception to the milder rule in the week ahead, where a Canadian air mass will briefly make its presence felt from Tuesday through Thursday.

These unusually warm conditions are highlighted in the next animation, which shows the temperature difference from average about a mile above Earth's surface. This level is often used by forecasters to assess the anomalous nature of air masses as it can be more uniform than patterns on the ground.

There are some signs that there may be more temperature fluctuations after Nov. 20, potentially caused by a loopier jet stream and the emergence of high pressure near Greenland. But signs indicate that cold shots will be generally short-lived as meteorological winter, starting Dec. 1, approaches.

In other words, don't pack away the T-shirts and shorts. Yet.