Background Extreme weather and temperature can impact human health and influence acute care need, particularly among older patients. Objective To examine how weather derived metrics compare with traditional temperature measures in capturing the impact of extreme weather on hospital admissions, particularly among older men and women. Design Observational Study Setting Hospital Admissions in Central Massachusetts from April 2021 to April 2024. Patients Inpatient admissions due to cardiovascular, stroke, renal, and pulmonary disease among adults. Measurements Daily Maximum of temperature metrics, Ambient Temperature, Wet Bulb Globe (WBGT) Temperature, Universal Thermal Climate Index (UTCI), and Heat Index Results We observed 83,469 hospital admissions that met the study inclusion criteria during the period under study; these were based on data from 44,156 individual patients (mean age 67.9 years; 50.8% male). In comparison with normal temperature indices, we observed a decreased risk for hospital admissions on extreme cold days as measured by ambient temperature (IRR: 0.66 [95% CI, 0.50-0.87]) and UTCI (IRR: 0.89 [0.83-0.95]) but an increased risk for hospital admissions on extreme warm days as measured by WBGT (IRR: 1.06 [1.01-1.13]) and UTCI (IRR: 1.06 [1.01-1.12]). Through stratified trend analysis, we observed stronger associations between weather variables and admissions among patients 65 years and older. Limitations Relatively focused area where temperature did not reach extreme heat thresholds often. Conclusion Strategies that consider weather patterns and their effects on acute care needs can be helpful in healthcare planning and hold potential to inform individual-level risk for exacerbation of neuro-cardio-pulmonary-renal conditions.