This week, work seems to be taking longer than usual. Each letter of that sentence was a burden; I paused and rewrote this one several times. I can come up with excuses: Perhaps too many meetings are making me distracted, or I wrote too many words last week and am out of inspiration. Possibly, though, I should blame the weather, the rising temperatures of late-June New York City.
Multiple studies have found that productivity plummets during sunny days, and that’s not the only negative effect researchers have noted. The weather, far from being just a relatively inconsequential topic of conversation, affects all manner of behaviors.
One study into the influence of temperature on people’s sense of well-being, found a particularly striking effect: “A day with temperature above 90[°F’ (relative to one in the 70s) has a bigger effect on the net affect than being divorced or widowed (relative to being married),” wrote the paper’s author Marie Connolly, professor of economics at the University of Quebec.
Connolly wasn’t making a serious argument here that a hot day is worse than getting a divorce; her study did not evaluate both circumstances and then draw a careful direct comparison. Instead, Connolly first examined the link between subjective well-being (based on data from the Princeton Affect and Time Survey) and weather, and then compared it earlier research showing that marriage is one of the strongest correlates of happiness and wellbeing.
The two studies are quite dissimilar, focusing on different time scales. The moment a couple decides to get divorced almost certainly correlates with a bigger drop in life satisfaction than the moment one steps outside on a very hot day. But the research on the link between marriage and life satisfaction doesn’t focus on the specific moment the study subjects got divorced; in that paper, the life satisfaction of someone who split from their partner four years ago is counted in the same bracket as someone who got divorced yesterday. Connolly’s temperature study necessarily focuses on a shorter time frame, measuring only the temperature of one day. Nevertheless, though, the point remains: Extremely hot weather has a dramatic impact on wellbeing.
That’s not summer weather’s only effect on human behavior. As Maria Konnikova previously reported in the New Yorker, stock prices go up on sunny days, likely influenced by investors’ optimistic moods. In addition, children do significantly worse on math tests when the temperature gets above 79°F, perhaps (the researchers behind that particular study suggest) because when it’s hot outside, the human body is less efficient at dispelling the heat created by brain activity, and this arguably affects mental capabilities such as working memory.
On the other side of the coin, prospective college students are more likely to choose an academic university if they visit on a cloudy day. (Clouds, apparently, make people appreciate more studious activities.)
There’s also significant research showing a link between temperature and violence: Violent crime rises along with the heat—but only up until 80°F, at which point it starts to fall again. Experts have theorized that the link between violence and heat can be explained by physiological changes such as increased heart rate and sweating, which are triggers for the nervous system’s flight-or-fight response. Or perhaps people are simply more uncomfortable under the broiling sun and therefore more irritable, and inclined to lash out.
But in general, there’s really no clear explanation why warmer weather causes any of these emotional changes in people. In some ways, what these studies prove above all else is just how hard it is to neatly explain human behavior, due to how many factors influence us at any one time. Consider all of the thousands of economic, psychological, and anthropological studies that evaluate how some given factor seems to affect humans—and which fail to take into consideration the weather on the day they analyze each of their human subjects.
And if weather can have such a huge impact, there’s likely other, hidden factors also influencing the results of those studies. To turn that thought on its head, who knows what other factors could confound the findings of the studies that specifically focused on weather. The news on that hot summer day, what participants had for breakfast, to whom they last spoke, and so many more factors all likely had an effect on each study participant’s responses to survey questions.
The same unpredictability and difficulty in neatly explaining causality is as true in everyday life as it is in academic studies—probably more so. We could be walking around thinking we’re annoyed at a dismissive comment or a missed train, when in fact the blazing heat has messed with our psyches and is sending us into a turbulent summer of sweat and misery.
We’re not fully at the whim of the weather, of course. Humans are, to a point, reflective creatures who are capable of making reasoned decisions and taking responsibility for our emotional well-being. But the environment, including the burning sun, does have an effect. Even if the weather doesn’t completely control you, sometimes it is ok to blame the heat for a bad mood.