[Objective] To address the limited spatial representativeness of traditional meteorological stations and to fill the research gap on climate change in the upper-middle Yarlung Zangbo River basin, this study analyzed the spatiotemporal variations of precipitation and temperature from 1979 to 2023, and quantified their contributions to runoff depth. The findings aim to provide a scientific basis for hydrological process understanding and water resource management in this datascarce mountainous region. [Methods] The TPMFD dataset (1/30°) supplied precipitation and temperature data, while SRTM DEM (12.5 m) supported terrain analysis. The basin above Yangcun station was delineated into 91 subbasins using ArcGIS hydrological tools. Four statistical methods were applied: Mann-Kendall test for trend and abrupt change detection, Morlet wavelet analysis for periodicity identification, subbasin statistics for spatial pattern analysis at multiple scales (whole basin, eastwest zones, northsouth banks), and multiple linear regression to quantify the relationship between meteorological variables and runoff depth. [Results] From 1979 to 2023, precipitation increased at 1.6-1.7 mm/a, and temperature rose by approximately 0.03 ℃/a. Abrupt change points were detected around 1995-2000 for precipitation and around 2000 for temperature, after which both variables showed significant increasing trends at 95% and 99% confidence levels. The precipitation growth rates were 1.60, 1.70, and 1.71 mm/a for the whole basin, source-Lazi, Lazi-Nugesha, and Nugesha-Yangcun, respectively, while temperature increase remained uniform at 0.03 ℃/a across subregions. Wavelet analysis revealed dominant 4-year and 12-year cycles for precipitation, with significant periods appearing during 1985-1995 and 2000-2020, and 3-year and 6-year cycles for temperature, with notable signals in 1990-2020. The mean annual precipitation was 508.3 mm, with summer contributing 73% of the annual total. Spatially, precipitation increased from southwest to northeast, and the northern bank received more precipitation than the southern bank; the southern bank displayed a central > eastern > western pattern. The mean annual temperature was -0.65 ℃, with seasonal means of -0.86 ℃, 6.84 ℃, 0.16 ℃, and -8.74 ℃ for spring, summer, autumn, and winter. Temperature decreased from the basin center toward surrounding mountain ranges, exhibiting a central>eastern>western distribution. The northern bank showed larger temperature gradients, with maximum center-to-edge differences reaching 9.10 ℃ in the east, while the southern bank showed smaller differences (maximum 3.83 ℃). Runoff depths at the Lazi, Nugesha, and Yangcun stations were 95.01 mm, 115.31 mm, and 153.76 mm, respectively, with increasing trends from west to east at rates of 2.12, 1.58, and 1.14 mm/a. Multiple linear regression demonstrated that precipitation was significantly correlated with runoff depth (r>0.8,t> 2, contribution >90%), whereas temperature showed no significant correlation (t< 2, contribution <1%). The influence of precipitation on runoff intensified from west to east and was more pronounced in interannual variability than in intraannual fluctuations. [Conclusions] The study area has experienced a warming and wetting trend over the past four and a half decades. Precipitation acts as the dominant factor controlling runoff generation, while temperature influences runoff indirectly through snowmelt, evapotranspiration, and related processes. The increasing contribution of precipitation to runoff from west to east reflects the spatial distribution of water vapor transport modulated by interactions between the Indian monsoon and westerlies. The significant spatiotemporal heterogeneity underscores the necessity of employing highresolution gridded datasets, such as TPMFD, to complement sparse station observations in complex mountain environments. These findings provide a theoretical foundation for hydrological modeling, water resource assessment, and climate adaptation planning in the Yarlung Zangbo River basin. Future research should incorporate glacier dynamics and land surface processes to enhance prediction of hydrological responses to climate change. The methodological framework combining subbasin delineation with multiscale statistical analysis offers a transferable approach for climate impact studies in other highaltitude basins.