Reconfiguration of Urban Leisure Space Use During Hot Periods: Evidence from Nanjing, China

Overall leisure activity can conceal substantial changes in how urban leisure use is distributed across functions, time, and space during hot periods. We analysed 917,186 user–venue–day leisure visits recorded on Weibo in central Nanjing during 2023–2025. Warm-season models compared representative daily maximum temperatures of 28 °C and 37 °C, while full-year records supported within-user comparisons of destination environments. Baseline estimated daily recorded visits were 8.54% higher under sustained 37 °C conditions. This association persisted with seasonal adjustment. The share of nature-based recreation fell from 22.37% to 18.88%, while heritage and tourism gained 1.18 percentage points. Nature-based recreation shifted relatively towards morning hours, and its effective density area decreased by 5.12%. Public cultural facilities showed an 8.20% reduction in effective density area. The cluster with the lowest median relative land surface temperature was a loss cluster, showing that a cooler surface thermal background did not translate into greater relative use. Full-year within-user comparisons showed 2.75 percentage points more surrounding water and 1.60 points less tree cover at destinations recorded on days at or above 30 °C; warm-season differences were smaller, with all 95% confidence intervals including zero. Heat-adaptation planning should consider function-specific use and conditions at heavily used destinations.