For many of the years I lived in Boston, the springtime weeks were  full of clear, sunny skies.

But every single weekend provided  soggy, miserable weather. What gives?!

Is it just my imagination that every  single weekend it seems to rain? Were the rainy days more noticeable because they were interrupting my weekend plans? Did a weather god curse the  Northeast United States??

Or is it some weird meteorological phenomenon? Funnily enough… it’s that last thing. Weather in New England can be oddly… punctual.

So here’s the science of the rainy weekend curse. [Intro] Rain in the spring is no  surprise to North Americans, with “April showers bring  May flowers” and everything. But in 2023, 2024, AND 2025, Boston, New York, and the rest of the Northeastern US were stuck with beautiful, sunny work weeks  and overwhelmingly rainy weekends. In both 2024 and 2025, Boston received stretches of at least 6  consecutive rainy weekends in the spring.

And from January through June, there were far more weekends  with rain than without. 2023 was an especially wet year, bringing record rainfall all over the Northeast. And by October, in New York and Boston, only 12 out of 42 of the  year’s weekends had been sunny. That’s rain during 80% of weekends!

At some point you start to think  that this can’t just be coincidence. So meteorologists took a deeper  look at the weather patterns trapping the Northeast indoors every weekend. It’s easy to forget that air is  a fluid, and that it has mass.

We live our whole lives in it, and  move through it so effortlessly, yet it’s constantly pressing  down on us and swirling about. Air is subject to the laws of fluid dynamics. On a planetary scale, those  effects can really add up!

We experience these effects as  weather, and meteorological events are all driven by differences  in temperature and pressure throughout the atmosphere. The jet streams have an especially big impact. You might have heard your airplane’s  pilot mention the jet stream.

It’s like a river of fast-moving air that  travels from west to east across the globe. But it affects way more  than just your flight time. Jet streams exist because of fluid mechanics.

The equator gets more sunlight than the poles do, which means the air is warmer  around the Earth’s middle. As the air gets warmer, it expands and rises,  creating a low pressure zone. On the other hand, the cold, dense air  at the poles forms a high pressure zone.

Air rushes from regions of high  pressure into regions of low pressure. On a global scale, this means that cold air from the  poles floods toward the equator, and light warm air drifts poleward above it. The cold air packets warm up at the equator, rising to replenish the low pressure zone, and the warm air packets cool down at the poles to sustain the high pressure zone.

This sets up a cycle of air constantly moving from equator to poles and back again. BUT don’t forget, the Earth is also rotating. Air rotates with the Earth, constantly  getting dragged to the east.

Because of this, the rising air from the equator never actually makes it to the poles— the Earth’s rotation, plus all the  bumpiness of the Earth’s surface, causes the circulation pattern to be split  into three different circulation cells. From the equator to about 30° north  or south, we have the Hadley cells. Beyond that are the mid-latitude cells, or Ferrel cells, and finally the polar  cells over the north and south poles.

The boundaries between two different  cells result in jet streams. They separate regions of cold and warm air, which means the jet streams are fueled by the Earth’s steady rotation and  that differential warming from the Sun. In particular, the northern polar jet stream is what keeps Arctic air over the Arctic.

And it’s strongest in the winter, when temperature differences are most stark. The polar jet stream also controls most weather in the mid-latitudes of the Northern Hemisphere— like Boston, which sits at about 42 degrees North. Another key thing about fluids is  that they’re really easily perturbed.

The jet stream is really just a river of air, so obstacles like a mountain range, open ocean, or just a random high pressure  zone can easily disturb it, and give it a little wiggle. When all these wiggles add up, the  jet stream settles into a pattern called a Rossby wave that encircles the pole. Usually, for the polar jet stream, this wave pattern will have  about four to six dips in it.

Sometimes these wiggles move north or south, and occasionally a trough might  disappear or reappear all of a sudden. Meteorologists refer to the jet  stream’s wiggles as “meandering”. How cute!

Maybe I should meander more For the most part, the Rossby  wave pattern is pretty stable, meaning the pattern doesn’t change all that much. But it will slowly rotate around the globe. In the springtime, more intense solar radiation adds energy to the air and the ocean.

Temperature differences between the arctic  and mid-latitudes become less pronounced, which weakens the jet stream. When our air river isn’t moving as fast,  it’s more sensitive to disturbances, so the Rossby waves can become even wavier, with the wave’s troughs dipping  to lower latitudes than before. This is important because storm patterns tend to follow the leading edge of these troughs.

The troughs carry low pressure zones— the warmer air we talked about earlier. Air at the boundaries of these low  pressure zones rushes in and flows upward. As it rises, it cools, and the water it carried  condenses to form storm clouds.

What this adds up to is that  the Rossby waves slowly rotate around the Earth, carrying storms with them as they go. Rossby waves move at a characteristic speed that depends on how many troughs they have. This means the broad river of air slowly rotates, so that the troughs change position.

And that cycle takes anywhere  between 5 and 10 days. See where I’m going with this? Sometimes, the troughs will be  spaced about seven days apart.

And sometimes, that pattern will  be centered on the weekends. Because once the Rossby wave takes shape  and gets stuck in one of its patterns, it can be really hard to break out. Rossby waves form naturally in the jet stream based on the Earth’s topography.

But sometimes other climate patterns can additionally amplify or  shape those wobbles and troughs. For example, persistent high pressure  zones can also set up “blocking patterns”, like one that often gets stuck over Greenland. The low pressure troughs must deflect  around the zone that’s “blocked”, forcing a specific shape into  the meandering jet stream.

And that can cause the whole shebang  to get stuck in a specific pattern – hello, soggy Saturdays. Rainy weekends aren’t the only consequence of these persistent anomalies in the jet stream. The jet stream also helps keep  Western Europe pretty temperate.

And it’s what keeps the Mediterranean  region warm and dry for most of the year. So while Boston and New York get hit  with perpetually rainy summer weekends, record breaking heat waves and  floods can get stuck over Europe. This isn’t just a summertime issue, either.

Destabilization of the jet stream is associated with polar vortexes and arctic blasts. During these events, pockets of arctic  air can push down from the Arctic circle, bringing extreme cold with them. These effects are increasingly common in the US, particularly over the Midwest  and Great Plains regions.

Hopefully in 2026, we won’t get  stuck in these weather patterns again that keep us stuck indoors! But if you live in the Northeast US, I am sorry to say that you might need to get  your vitamin D dose on your weekday lunch breaks, and settle for indoor museums  and umbrellas on the weekends. [ outro ]