Recent studies performed in the Houston-Galveston-Brazoria (HGB) area indicate that some industrial air pollutant emission sources exhibit high temporal variability that can lead to very rapid ozone formation, especially when emissions include highly reactive volatile organic compounds. This motivated the collection of a unique data set of air pollutant emissions, from industrial facilities, reported with an hourly time resolution. The industrial flares portion of this data set was utilized in this work to characterize and model the highly variable temporal patterns of flare emissions at petrochemical facilities. Petrochemical and chemical manufacturing flares were grouped into categories based on industrial process they service, chemical composition of the flared gas, and the temporal patterns of their emissions. Stochastic models were developed for each categorization of flare emissions and provide representative temporal profiles for flares in specific types of operations in the petrochemical and chemical manufacturing sectors.