MIT Technology Review recently highlighted a new research program at Stanford University that shows how weather can affect mood. They are using Twitter to analyze the relationship. The researchers began with a database of tweets geotagged to one of 32 major urban areas in the US, such as New York, Chicago, Los Angeles, and San Francisco. They then mined the tweets for indications of mood, filtering out tweets about national or international events, and then searched for correlations with the weather. The researchers say some moods are clearly correlated with certain types of or changes in weather. For instance, temperature drops generally make people happier, while higher temperatures make people angrier. Drastic temperature changes make people uncomfortable and snow is correlated with negative moods.

You can read more about this research at the MIT Technology Review here.