Many factors affect the rate of photosynthesis, firstly, temperature commonly accelerates the rate of chemical reactions, but can lead to protein denaturalization, or cause water to evaporate.
Light intensity favours the process of photosynthesis as light is the source of energy of this reaction.
Lastly, water availability is also necessary as it is one of the sustrates of the chemical reaction to form glucose:
6CO2 + 6H2O → C6H12O6 + 6O2
Even though all of this factors tend to contribute to photosynthesis rate, all of them have a optimal range, and an excess if them can be detrimentl for the reaction and the plant itself.