As climate change accelerates and populations age, the cognitive health risks of extreme climate exposure is increasingly critical. This study investigated whether exposure to extreme heat, cold, and high precipitation affects cognitive function in older adults and whether age-friendly home modifications moderate these relationships.

We linked three waves of the Chinese Longitudinal Aging Social Survey (2016, 2018, 2020; 21,789 observations from 7,263 adults aged ≥ 60) to prefecture-level daily meteorological data. Extreme climate exposures were defined using location-specific percentile-based thresholds. Cognitive function was measured with the modified Mini-Mental State Examination. Fixed-effects regressions estimated climate-cognition associations, and propensity-score matching combined with difference-in-differences tested whether home modifications moderated these associations.

All three extreme climate exposures significantly reduced cognitive function: extreme heat (β=-.006, p =.004), extreme cold (β=-.007, p =.013), and extreme high precipitation (β=-.047, p < .001). Subgroup analyses revealed women were especially sensitive to extreme cold, and adults aged ≥ 80 to extreme heat. Age-friendly home modifications significantly improved cognitive function and buffered adverse effects of extreme cold (β=.046, p < .001) and high precipitation (β=.065, p=.008), with physical accessibility and functional safety modifications providing protection. These protective effects operated through maintaining social participation, reducing depressive symptoms, and preserving functional capacity during adverse weather. Moreover, benefits were larger for the oldest-old, rural residents, and those in northern or central China.

Extreme climate exposures accelerate cognitive decline in older adults, while age-friendly home modifications provide moderating protection. Integrating such modifications into national climate-adaptation and healthy-aging strategies could enhance cognitive resilience in rapidly aging societies.