Weather-related variables (temperature and rain) are examined for their association with daily cigarette smoking. Prior research has examined how the average monthly temperature and summer versus winter months are related to smoking, but daily fluctuations in weather have not been examined previously. The current research tests whether daily changes in weather are related to young adult cigarette use. In addition, nicotine dependency is tested as a moderator of such associations. Nine hundred and twelve participants were recruited to complete weekly measures of cigarette smoking for 35 weeks. Participants provided weekly self-reports of daily smoking for the last week and completed measures of nicotine dependence. In addition, data was obtained on daily temperature and presence of rain. A longitudinal growth curve model was calculated using daily temperature and rain data to predict daily cigarette smoking. A positive linear effect and negative quadratic effect of temperature was found along with a negative effect of rain. Nicotine dependency did not moderate the effect of temperature or rain on smoking. This study is the first to use daily measures of temperature and rain and corresponding daily measures of cigarette smoking to examine possible associations. Results support the relevance of weather-related variables in the prediction of cigarette smoking and the importance of considering environmental factors in understanding smoking behaviour.