Researchers found that flirting is more likely to have a positive outcome on sunny days.
Nicolas Gueguen of the University of South Brittany conducted the study in which an 'attractive' 20-year-old male approached 18-25 year old women walking alone in the street and asked them for their phone numbers.
The women were solicited on both sunny and cloudy, but not rainy days, when the temperature was about the same, Alpha Galileo Foundation reported.
In the past other environmental factors have been found to make people more likely to flirt or exchange phone numbers - the presence of pleasant smells, romantic music or certain colours have all been found to have an effect.
Previous research has also shown how the weather can affect certain social behaviours - sunshine makes people more likely to help strangers or answer a survey, and people tend to leave bigger tips in restaurants on sunny days.
But this is the first research to explore how the weather may influence courtship or dating behaviour.
It was found that women were more receptive to being approached and flirted with - and give out their phone numbers - on sunny days: over a fifth - 22.4 per cent - of women did so when the Sun was out, as opposed to 13.9 per cent on the cloudy days.
Researchers say the message seems clear: flirting is more likely to have a positive outcome on sunny days. But Gueguen said the sunshine or other factors may after all have improved the attractive 20 year old male's flirting skills on those days.
Other atmospheric conditions such as windiness or humidity were not accounted for. And, perhaps most crucially, the research was conducted in France, where "men traditionally approach women in romantic relationships".
The study was published in the journal Social Influence.