Chaotic March weather has a surprising secret

As its final days wind down, weather in March 2026 has been one for the record books. It showed why old sayings endure and rivaled college basketball for “March Madness.”

True to the proverb, the month came “in like a lion,” and later echoed Shakespeare’s warning to “beware the ides of March.”

Relentless, record-breaking heat persisted in the West. Powerful storms and bouts of polar air blew through the Central and Eastern U.S., bringing extreme swings in temperature within hours. Hawaii endured flooding rains in a string of kona lows.

It may come as a surprise, but these weather systems also illustrate how connected we are by larger patterns that move around in our atmosphere.

Though we tend to focus on what’s going on in our own regions, “all the global patterns are connected through jet stream interactions and waves around the planet,” said Daniel McEvoy, a research scientist with the Western Regional Climate Center. “The patterns kind of feed off each other and drive weather across the continent.”

Scientists don’t yet fully understand all the triggers and feedbacks in the atmosphere, but they know things taking place in and over the Pacific Ocean influence weather across the U.S. That influence travels through the fluid environment in the atmosphere via planetary waves, said Jonathan Rutz, an atmospheric scientist at the Center for Western Weather and Water Extremes.

Much of the activity is linked to the jet streams, currents of typically very fast-moving air in the mid-latitudes of both the Northern and Southern hemispheres, Rutz said. The jet streams exist because of temperature differences in the atmosphere between the poles and the equator that create the strong wind fields. Depending on conditions in the atmosphere, the jet stream can be fairly flat and fast moving or meander.

High pressure systems, usually related to clear and warm conditions, and low pressure systems, often linked to storms, kind of ride around the globe on the jet stream, McEvoy said. When they’re blocked, they can linger over a region for days or weeks.

When the jet is streaming rapidly, planetary waves ripple along quickly in the atmosphere, bringing fronts with more frequent changes in the weather, Rutz said. When the jet slows, the number of planetary waves decreases, and the patterns become more amplified, with the jet stream developing big dips and peaks, he said. “That’s when we see weather making the news.”

In these cases, the same patterns persist over the same areas, Rutz said. That’s how the atmosphere could set up the repeated kona lows over Hawaii, atmospheric rivers into the Pacific Northwest and dominate the West with hot, dry air and colder air pushing into the East.

“Sometimes it can be a little bit chicken and egg to determine exactly where that pattern started or what the trigger was,” Rutz said. He describes the process as interconnected, simultaneous phenomena that develop “and then kind of lock into each other, almost like pieces of a puzzle.”

Kona lows

The low pressure system that generated the rain over Hawaii is a recurring winter phenomenon in the region. The pattern is commonly called a “kona low.” Kona is the Hawaiian word for leeward and the activity often brings wind and rain to the leeward side of the islands.

Incredible amounts of rain fell with the lows in March, according to a National Weather Service summary using preliminary data. Rainfall amounts ranged as high as 52 inches on Oahu, 54.92 at Summit on Maui and 42.2 at Puu Waawaa on the island of Hawaii.

Devastating flooding occurred in North Shore communities on Oahu, where homes were swept away and residents needed rescuing.

Unprecedented heat wave

A persistent high-pressure system fueled a lack of precipitation in the West and enduring triple-digit temperatures. By March 19, weather data shows monthly all-time high record temperatures were broken in at least 11 states where the data goes back at least 70 years.

“It was just really an extraordinary event, for several reasons,” including the magnitude and duration of the heat, McEvoy said. “Previous records for statewide monthly record are being broken by 4, 5 and 6 degrees, which is really a huge jump in magnitude,” McEvoy said. “The magnitude of the heat wave was more like early summer.”

The high temperature in Yuma, Arizona on March 20 reached 109 degrees, 28 degrees above its 30-year normal.

Among the March records in the U.S., 492 locations broke a previous monthly high, and at least 300 broke records for their warmest monthly overnight low. More than a thousand other records were set for daily maximum temperatures or warm overnight lows.

Weather whiplash and climate change

The same pattern that created the rain over Hawaii, and atmospheric rivers in the Pacific Northwest also brought high winds and snow storms and a variety of extremes to the eastern half of the United States during the month. A powerful storm March 14 — 16 canceled flights, prompted states of emergency and brought the first blizzard warnings in 15 years to Milwaukee.

Several scientists this week pointed to these extremes and the whiplash between extremes as potential evidence of the warming climate.

Unusual heat waves like the one in the West have been discussed in climate change literature, with forecasts that they’ll increase in severity and duration, McEvoy said.

Jennifer Francis, a senior scientist at the Woodwell Climate Research Center, is among the scientists pointing to intense heat waves in the Pacific Ocean and the likelihood they’re influencing the jet stream and the persistent warm pattern over the western U.S.

“They’re dominating the influence on the jet stream and anchoring these patterns in place that create these very persistent weather conditions,” Francis said in a webinar this week.

Scientists with World Weather Attribution, an organization working to understand how climate change is affecting weather events, conducted a rapid analysis of the rare western heat wave and found it would be “virtually impossible” without human-caused climate change. In just a decade, such an event has become about four times more likely due to climate change, the analysis concluded.

The wild swings in temperatures can be unsettling for people, Francis and others said, and also reflect the realities of a warming climate. For example, the reactions to the cold in the Northeast suggest people have become so used to milder winters that when temperatures plunge back to those more typical decades ago, they seem even more severe.

Dinah Voyles Pulver, a national correspondent for USA TODAY, covers climate change, weather, the environment and other news. Reach her at dpulver@usatoday.com or @dinahvp on Bluesky or X or dinahvp.77 on Signal.