Nicolas Guéguen of the University of Southern Brittany, who has previously investigated how wearing red lipstick can increase a waitress's tips, led a study in which a handsome 20-year-old male approached 500 women between 18 and 25 years old walking alone in the street and asked them for their phone numbers.

The women were solicited on both sunny and cloudy (not rainy) days, when the temperature was about the same.

Women were more receptive to flirting when being approached, and were more willing to give out their phone numbers, on sunny days. More than 22% of women did so when the sun was out, as opposed to just under 14% on the cloudy days.

Past research has found that people are more likely to flirt and exchange phone numbers in the presence of pleasant smells, romantic music, or certain colors, noted the research team.

Findings, announced January 28, were published in the journal Social Influence.

Click here to access the study.