To reach the conclusion, a group of male subjects were asked, at different times of the year, to rate photos of women. They gave their highest scores in the winter and autumn, and their lowest scores in the summer.
Researchers at University of Wroclaw in Poland who carried out the experiment believe the seasonal variation may have an impact on mate choice and on levels of adultery.
There is no clear explanation for the variation, but the researchers say one theory is that fewer female bodies are on display in the winter, so the rarity makes them more attractive.
The study has been published in the journal Perception.
The researchers also tested how attractive the men in the study found their own partner. The results showed the same seasonal pattern, with a peak in autumn and winter. But when the men were asked to rate their own attractiveness, there was no seasonal variation.
The researchers found the same pattern of results in men of all ages, and in those living in urban and rural areas.
"Since in summer men are much more often exposed to more uncovered women's bodies than in winter, our prediction was that stimuli presented to men in summer will be assessed as less attractive than the same stimuli presented to the same men in winter," Telegraph quoted the researchers, as saying.
"As predicted, ratings of body and breast attractiveness were lower in summer than in winter. This effect may also contribute to observed behavioural fluctuations related to human male-female interactions. The effect we found might cause seasonally different levels of male assessment of female attractiveness or affect males'' mate choice decisions.
"It is also possible that such seasonality might be related to some fluctuations in sexual activity and therefore might be related, for example, to some yearly fluctuations of adulterous behaviour," they added.