BACKGROUND: Previous studies have demonstrated the seasonal variations of non-variceal upper gastrointestinal bleeding (UGIB), but there is scanty data on lower gastrointestinal bleeding (LGIB) and the association with other meteorological parameters. METHODS: We included all patients hospitalized for UGIB and LGIB between 2009 and 2018 in Hong Kong. The monthly age-standardized and sex-standardized GIB incidences were fitted to meteorological data including average temperature (AT), maximum temperature (MaxT), minimum temperature (MinT), temperature range (TR), average precipitation, average atmospheric pressure (AtomP), and average relative humidity after adjusting for prescriptions of aspirin, proton pump inhibitors, and Helicobacter pylori eradication therapy using the autoregressive integrated moving average model. RESULTS: Despite a gradual decline in UGIB incidences, the incidences of UGIB were still higher in winter months. The incidence and fluctuation of both UGIB and LGIB were higher in the older age groups, especially those ≥80 years. The seasonality was only identified in those ≥60 years for UGIB, and only in those ≥80 years for LGIB. UGIB incidence was inversely associated with AT, MaxT, and MinT, but positively associated with TR and AtomP. LGIB was also significantly associated with AT, MaxT, MinT, and AtomP. CONCLUSION: Despite the changes in GIB incidences, the seasonal patterns of GIB were still marked in the elderly. With the aging population, the impacts of seasonal variations on GIB incidences could be considerable.