Key weather averages for Tokyo in July. 1  29. 29°C max day temperature. 2  5. 5 hours of sunshine per day. 3  19. 19 days with some rainfall. 4  22. 22°C min night temperature. 5  14. 14 hours of daylight per day. 6  H. 7  128. 128 mm of monthly rainfall. 8  10. 10 (Very High) UV index. 9  24. 24°C sea temperature.