Background Outdoor exercise is an enjoyable way for individuals to improve fitness, but it is dependent on weather conditions. This study examines the association between weather conditions and outdoor exercise after adjustment for age, sex, race, and socioeconomic status. Methods We used data representative of American adults from the University of Michigan/Thomson Reuters June 2013 surveys of consumers (core and supplement) to investigate self-reported exercise behavior in summer and winter. Multivariate multinomial logistic regression models estimated the odds of delayed or indoor exercise compared with outdoor exercise. Results Of the 502 respondents, 16.3% did not regularly exercise outdoors (i.e., at least once a week), and many would delay exercise both in summer (51.8%) and winter (43.9%). Individuals listing rain as the predominant adverse weather condition had 3.29 times higher odds of exercising indoors (95%CI, 1.33-8.17) and 3.49 times higher odds of delaying exercise (95%CI, 1.33-8.17) compared with those mentioning heat as the predominant adverse condition. Individuals for whom ice or snow was an adverse winter weather condition were more likely to delay exercise (OR: 3.22; 95%CI: 1.14-9.08), compared with those concerned with cold. Conclusion This study found that race, age, and education exacerbate the negative effects of adverse weather conditions on the decision to exercise outdoors. Accordingly, any recommendation for an individual to exercise outdoors should be combined with an evaluation of the individual's outdoor environment along with strategies for the individual to continue exercising, indoors or outdoors, when adverse weather is present.