Lily Pien, an allergist at the Cleveland Clinic, drove to work earlier this week in snow and hail. The next day it was 65 degrees and sunny.
Many parts of the United States have seen wild weather swings and unseasonable conditions in recent days. The West is shivering in record cold, while the Southeast and Mid-Atlantic are experiencing unusual heat for February, including a pattern of springlike days on top of cold snaps — and vice versa.
One D.C. radio announcer Wednesday morning forecast a “record high” 80 degrees for Thursday, then warned: “Bundle up on Friday.”
Such fluctuations bewilder plants and animals, disturb the balance of delicate ecological systems and can exacerbate human health problems, especially among those with existing medical conditions, experts said. These changes can aggravate allergies, cause infections and worsen other more serious conditions, such as heart disease, they said.
“That jolt to your system can bring out all sorts of problems,” said Aaron Bernstein, interim director of the Center for Climate, Health, and the Global Environment at Harvard T.H. Chan School of Public Health (Harvard Chan C-CHANGE). “Going from 40 degrees to 80 degrees might not be a big deal for relatively healthy people, but could be for certain people, such as outdoor workers and people with chronic medical problems and other risks.”
The human body has the ability to acclimate to temperature change, “but it doesn’t kick in within a span of a few hours,” he said. “It takes many days — up to two weeks — to get acclimated.”
Gaurab Basu, co-director of the Center for Health Equity Education & Advocacy at the Cambridge Health Alliance, agreed. “Our bodies are a delicate equilibrium and working hard to maintain a certain body temperature,” he said. “They have to find ways to compensate for extremes.”
Sudden weather changes make us vulnerable to infection
Sudden temperature and humidity changes can affect the nose, making someone more vulnerable to bacterial and viral infections. Lower humidity, for instance, can lead the nose to dry up, “making the nasal tissues more susceptible to possible infection,” Pien said.
They also can prompt symptoms among those who have allergies — and even among those who don’t, including people who suffer from nonallergic rhinitis or allergy symptoms with no identified cause, Pien said.
“The nose is comprised of mostly blood vessels, which constrict when it is cold, and dilate with higher temperatures and more humidity,” she said. “When the weather goes back and forth in a 24-hour period, you can go from a runny nose to dry nose rather quickly.”
Temperature highs and lows raise mortality risk
These sudden changes in temperature can also be bad for the heart. Heat causes stress in the body and stress hormones can strain the heart, Bernstein said. Cold can cause hypothermia and lead to thicker blood that is “more prone to creating blood clots, leading to strokes, heart attacks and clots in the extremities,” he said.
A study in May in the Lancet Planetary Health journal found that over time these abrupt temperature shifts are associated with increased mortality.
Deaths related to these sudden jumps partly depends on the previous day’s temperature, Bernstein said. “It’s probably worse if you go from a relatively cooler temperature of 60 degrees to 95 degrees than if you had been in the 80s the day before and went to 95,” he said.
The impact on our bodies depends on the kind of temperature change. The body’s response is stronger when we move from cooler to very hot temperatures. A shift to 80 degrees is sudden in the midst of winter, and our bodies aren’t prepared, Bernstein said. People also may be wearing winter clothing, which may cause overheating. “All of this plays into increasing deaths when there is a big shift,” he said.
Weather changes can trigger migraine and joint pain
Studies also suggest that weather changes can trigger migraine and possibly other types of headaches.
One study found that a temperature increase of 5 degrees Celsius (9 degrees Fahrenheit) was associated with a 1 percent increase in the risk of emergency department visits for migraine, said Elizabeth Loder, professor of neurology at Harvard Medical School.
A second study looked at many weather variables — not just temperature — such as humidity, air pollution and barometric pressure changes and concluded that higher temperatures and lower barometric pressure were related to a higher risk of having any kind of headache, not just migraine, she said.
“It can be difficult” however “to tease out whether it is the temperature changes themselves, or whether other factors associated with wild weather swings, such as rapid changes in barometric pressure, humidity, pollution, might be playing a role,” Loder said.
There also may be some truth to those who insist their joints know when weather changes are imminent, said Nicholas DiNubile, a Philadelphia-area orthopedic surgeon and spokesman for the American Academy of Orthopaedic Surgeons.
“This is especially true if you have arthritis. Joints can act as barometers sensing especially rapid change in barometric pressure,” he said. “So some individuals, especially those with arthritis, will ache more with certain weather shifts and storms.”
Weather shifts now affect allergies, ticks and mosquitoes later
Within the broader context of climate change, these anomalies are playing out against a backdrop of “flowers that are blooming too early, and insects — vectors of disease — having different breeding seasons,” Basu said. “Unseasonable heat in February is changing the breeding seasons of ticks and mosquitoes which bring important diseases to human populations.”
The temperature fluctuations also confuse plants, and they will suddenly “release a lot of pollen that doesn’t follow historic trend lines, and this can affect asthma, rhinitis,” and other body systems, he said.
With the likelihood of such sudden swings increasing in the coming years, Bernstein believes people — in particular those with chronic medical conditions — should pay attention to their potential risks and protect themselves when these swings occur.
“It’s important to appreciate that going from 40 to 80 is a big jump,” he said. “We need to take the usual precautions, especially for people at risk for heat-related illness and make sure they can keep themselves safe.”
