The importance of emotion in risk perception has been well documented in field and experimental studies. However, little is known about its role in everyday life. On thirty occasions over ten consecutive working days, ninety-four participants were prompted at random - via mobile telephones - to report on their emotions and to assess perceived risks. Subsequently, risks associated with six occasions were re-assessed. Emotion was found to explain significant variance in risk perception over and above "reason" (assessed severity and possibility of risks) and to contribute to the tendency to assess risk lower in retrospect than when experienced. Our investigation illuminates the pervasive role of emotion in everyday risk perception and the value and feasibility of collecting meaningful samples of naturally occurring behavior with simple technology.