Does cold weather cause colds? What the evidence actually shows

Cold weather does not, by itself, give you a cold: colds are caused by respiratory viruses, and you cannot catch one from temperature alone. But the folklore is not simply wrong — a small randomised trial and two mechanistic studies suggest that chilling the body and breathing cold air can weaken the nose's frontline antiviral defences, making it more likely that a virus you have already met takes hold and turns into symptoms [s1][s2][s3].

The experiment that tested the folklore

The most direct test came from the Common Cold Centre at Cardiff University, published in Family Practice in 2005 [s1]. Researchers randomised 180 healthy volunteers to either chill their feet in cold water or a control procedure, then had them score cold symptoms twice a day for four to five days [s1]. Chilling produced no acute change in symptoms at the time (p=0.62) — nobody sneezed on cue — but over the following days, 13 of 90 chilled subjects reported a cold versus 5 of 90 controls (p=0.047), and mean total symptom scores for days one to four were higher in the chilled group, 5.16 against 2.89 (p=0.013) [s1]. The authors concluded that acute chilling of the feet causes cold symptoms in around 10% of people chilled [s1].

The interpretation matters as much as the numbers. The study did not show that cold water infected anyone; it suggested that chilling, by constricting blood vessels in the nose and dampening local defences, can let a virus already present tip over into a symptomatic cold. Tellingly, the 18 subjects who did develop a cold reported suffering more colds each year than the 162 who did not (p=0.007), consistent with the idea that chilling unmasks an infection in the already-susceptible rather than creating one from nothing [s1].

Why a cold nose is a friendlier nose for a virus

Two later studies fill in the biology, and both point the same way: temperature changes the contest between virus and host, not by summoning a virus but by shifting the odds. A 2015 study in the Proceedings of the National Academy of Sciences found that most human rhinoviruses — the commonest cold viruses — replicate more robustly at the cool temperatures of the nasal cavity, 33–35°C, than at the 37°C of the body's core [s2]. Working in mouse airway cells, the team showed the reason lies partly with the host: infected cells mounted a stronger antiviral interferon response at 37°C than at 33°C, so the cooler the tissue, the weaker the local defence and the freer the virus to grow [s2]. When the researchers knocked out the cells' virus-sensing machinery — the MAVS signalling protein or the type I interferon receptor — the virus replicated more freely, especially at 37°C, which ties the temperature effect directly to that innate immune pathway rather than to the virus alone [s2].

A 2023 study in the Journal of Allergy and Clinical Immunology added a second cold-sensitive defence in the nose itself [s3]. It described a "swarm" of extracellular vesicles that nasal cells release, via Toll-like receptor 3 signalling, when they sense a virus [s3]. These vesicles neutralise virus particles directly by binding them through surface receptors including LDLR and ICAM-1, and they ferry a protective microRNA, miR-17, into neighbouring cells [s3]. Cold exposure impaired the whole system — reducing how many vesicles the nose released, and blunting both their microRNA cargo and their virus-binding strength — which the authors offered as a direct mechanistic explanation for why upper-respiratory infections rise in the cold season [s3].

The honest synthesis

Put together, the evidence supports a careful version of the old warning rather than the literal one. Cold weather cannot manufacture a virus, and staying warm will not make you immune to one. What cold appears to do is lower the nose's guard — through cooler tissue that favours viral replication and a weaker interferon response [s2], and through a suppressed vesicle defence [s3] — so that exposure is more likely to become illness [s1]. That is only part of winter's story; indoor crowding, drier air and more time spent close to other people all push in the same direction, and the trial evidence in humans is small. But "wrap up warm" is not pure superstition. This article is informational and not medical advice.

For related coverage, see how to tell a cold from flu, COVID and RSV and why antibiotics do not treat colds.

Sources

• Acute cooling of the feet and the onset of common cold symptoms — Family Practice, 2005-11-14
• Temperature-dependent innate defense against the common cold virus in mouse airway cells — Proceedings of the National Academy of Sciences, 2015-01-05
• Cold exposure impairs extracellular vesicle swarm-mediated nasal antiviral immunity — Journal of Allergy and Clinical Immunology, 2022-12-06