Ok, this is a bit off topic, but I thought it a funny insight from a new study: After looking at 1.1 million online reviews for 840,000 restaurants in more than 32,000 cities across the country, researchers have found that the weather outside can be just as significant a factor for reviews as what happens inside a restaurant. The study shows evaluations written on rainy or snowy days, or very cold or hot days, are more negative than those written on nice days. The study also found a nationwide spike in the number of reviews written during the summer, but July and August were the worst months of the year for ratings. November was the best.

Abstract of the research:

Online recommendation sites are valuable information sources that people contribute to, and often use to choose restaurants. However, little is known about the dynamics behind participation in these online communities and how the recommendations in these communities are formed. In this work, we take a first look at online restaurant recommendation communities to study what endogenous (i.e., related to entities being reviewed) and exogenous factors influence people’s participation in the communities, and to what extent. We analyze an online community corpus of 840K restaurants and their 1.1M associated reviews from 2002 to 2011, spread across every U.S. state. We construct models for number of reviews and ratings by community members, based on several dimensions of endogenous and exogenous factors. We find that while endogenous factors such as restaurant attributes (e.g., meal, price, service) affect recommendations, surprisingly, exogenous factors such as demographics (e.g., neighborhood diversity, education) and weather (e.g., temperature, rain, snow, season) also exert a significant effect on reviews. We find that many of the effects in online communities can be explained using offline theories from experimental psychology. Our study is the first to look at exogenous factors and how it related to online restaurant reviews. It has implications for designing online recommendation sites, and in general, social media and online communities.