Based on our ARIMA regression coefficients for temperature, January, and May, we estimate that 32.1% of total hip fractures in January (the peak incidence month) are attributable to the season effect among seniors aged 75+ years, 17.2% among those aged 65-74 years, and 11.5% among those aged 45-64 years. We find that in a sub-tropical climate the effects of winter on hip fracture propensity is significant and increases with age. The policy implications are discussed.