We use Dutch travelers’ data for a period of 10 years (1996-2005), and locally and hourly measured meteorological data. Daily travel demand measured by number of trips is modeled as a negative binomial process. Our results suggest strong effects of weather on transportation and strong substitution of travel modes at extreme temperatures. During extreme cold weather, biking is substituted by increase in public transport and walking. During extreme warm weather, car and public transport is substituted by bicycle.