Greenhouse and field studies were conducted to assess the effects of water stress on almond leaf temperatures and Pacific spider mite,Tetranychus pacificusMcGregor, developmental times. Egg-to-egg developmental times on water-stressed almond trees were 11% faster than developmental times on nonstressed trees. Leaf surface temperatures on the stressed trees averaged 2.1°C higher than those on the nonstressed trees. Accumulated degree hours for egg-to-egg development were not significantly different among the mites from the stress and nonstress treatments. Thus, the faster developmental times for the mites on the stressed trees were the result of the higher leaf surface temperatures. Mean daily leaf canopy temperatures from 4-yr-old, water-stressed almond trees were 2.0°C higher than control trees under field conditions. Leaf canopy temperature differences were significantly correlated with differences in predawn leaf water potentials between the water-stressed and control trees. Mature almond trees under an irrigation regime of 55% evapotranspiration (ET) had significantly higher afternoon leaf canopy temperatures than trees under regimes of 85 and 100% ET. Increased leaf surface temperatures in water-stressed almond trees have the potential for accelerating increases in spider mite populations.