Does warm weather impact COVID-19?

Various studies examine the impact of humidity, temperature, rain, and sunshine on COVID-19.

man at the beach with coronavirus mask
  • Researchers around the world have been working to analyze and understand this virus since the global pandemic started earlier this year.
  • While the first SARS-CoV virus (2003) did not circulate long enough for researchers to distinguish any specific seasonal pattern, daily weather did have an impact on the number of cases.
  • Other studies from China, Australia, Brazil, and the UK take a look at how our weather can impact the transmission of COVID-19.

Many people believe warmer weather protects us from respiratory illnesses - but the reality is that COVID-19 is unlike many of the other respiratory illnesses we've seen. Researchers around the world have been working to analyze and understand this virus since the global pandemic started earlier this year.

    How does weather impact virus transmission?

    COVID-19 virus SARS-CoV-2 under microscope weather virus

    How does weather impact the COVID-19 virus?

    Image by MIA Studio on Shutterstock

    Studies of the first SARS-CoV (in 2003) might help us understand.

    While this virus did not circulate long enough for researchers to distinguish any specific seasonal pattern, daily weather did have an impact on the number of cases. According to this study, new cases of SARS-CoV were 18x higher in lower temperatures (under 24.6°C).

    Cold weather impacts your likelihood of getting sick in different ways.

    One factor, according to Sciencing, that may increase your susceptibility in cold weather is how your sinuses respond to the humidity and temperature changes. Your nose is a natural air filter for your body. When you spend time in cold temperatures, your nasal passages dry out due to the constriction of blood vessels. When you return to warmer temperatures (like coming inside after time spent out in the cold), the sudden influx of moisture can cause your nose to run.

    This usually forces you to breathe through your mouth, robbing you of the filter and making you susceptible to viruses or bacteria in the air.

    Cold weather = more time spent indoors, which can increase the likelihood of transmission.

    Regardless of the weather, it takes exposure to a virus to get a virus. One common reason why virus infections may become more common during cold months is that more people are spending time indoors (and together).

    As research has determined, social distancing can heavily impact the spread of the COVID-19 virus. Being clustered closer together indoors can increase the likelihood of transmission, giving the effect of the virus spreading faster in the colder months.

    The weather and COVID-19 studies from around the globe

    concept of condensation humidity impact COVID-19 condensation on window

    How do things like humidity, rainfall and sunshine impact the spread of COVID-19?

    Photo by matuska on Shutterstock

    Laboratory and observational studies of COVID-19 patients have shown there is an impact of humidity on SARS-COV-2.

    Humidity and its impact on COVID-19:

    A lab-generated aerosol of SARS-CoV-2 was stable at a humidity of 53 percent at room temperature (23°C). The virus had not degenerated much, even after 16 hours, and was more robust than SARS-CoV.

    Although laboratory studies cannot be used to explicitly explain how the virus will act in the real world, these findings are very important in deepening our understanding of the virus and its transmission.

    Another study in China (with more than 50 cases of COVID-19) found a link between humidity and reductions in COVID-19 cases. In this simulation, the team measured humidity as absolute humidity (the total amount of water in the air) and found that for every gram per cubic meter in absolute humidity, there was a 67 percent reduction in COVID-19 cases after a lag of 14 days.

    Similar studies (with similar results) have been conducted in Australia.

    Rainfall and its impact on COVID-19:

    Rainfall may also impact the spread of the virus. Research out of Brazil looked at rainfall worldwide and confirmed a pattern: for each average inch per day of rain, there was an increase of 56 COVID-19 cases per day. There was no link found between the COVID-19 deaths and rainfall.

    Sunshine and its impact on COVID-19:

    A Spain study found (after 5 days of lockdown) the longer the hours of sunshine, the more cases there were of the virus. This positive association held true with a lag (between sunshine hours and cases) of both 8 and 11 days.

    However, it's important to note that this actually contradicts findings from Influenza research, which suggests a lower transmission with longer hours of sunshine. While influenza and COVID-19 are obviously different, it's interesting to note this contrast, as they are both viral infections.

    While all of these studies are interesting, does it really prove COVID-19 is impacted by weather?

    Research out of Oxford actually lists reasons why people should not use these observational studies on the weather and COVID-19 cases to establish if the virus is more or less transmittable based on the season.

    While it's important to note that there are still things we don't know about COVID-19 and that each country has different testing and studying methods, the more we know about how this virus behaves in different climates the more we can work to prevent further infection.

    This is what aliens would 'hear' if they flew by Earth

    A Mercury-bound spacecraft's noisy flyby of our home planet.

    Image source: sdecoret on Shutterstock/ESA/Big Think
    Surprising Science
    • There is no sound in space, but if there was, this is what it might sound like passing by Earth.
    • A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
    • Yes, in space no one can hear you scream, but this is still some chill stuff.

    First off, let's be clear what we mean by "hear" here. (Here, here!)

    Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.

    All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.


    Image source: European Space Agency

    The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.

    Into and out of Earth's shadow

    In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.

    The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."

    In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."

    When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.

    Magentosphere melody

    The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.

    BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.

    MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.

    Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.

    Photo by Martin Adams on Unsplash
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