In this paper, we use data from Google Trends to estimate the effect of temperature on a set of sexual and mate-seeking keywords. We find that high temperatures increase searches for pornography but suppress searches for online dating services, while cold temperatures do the opposite. This is consistent with substitution between activity based on temperature – when it is hot, people prefer sexual and mate seeking activities which are more solo, while when it is cold they prefer to seek out another person. We also find dynamic effects for online dating searches, but not pornography. We find no difference across US regions, but we do find that our results are driven by rich states, which are more likely to have higher levels of internet penetration.