Hey Saima,

You can use weather generator to generate daily weather data from monthly weather data. You need to make sure that you have monthly statistical characteristics of observed weather data. Use these statistical characteristics of observed weather data as input to weather generator and generate daily weather data for your desired time period.

For further detail see the link to IPCC web page where they have a brief description about the use of weather generator:

http://www.ipcc-data.org/guidelines/pages/weather_generators.html

Best of luck

Thanks a lot Firdos Khan and Ina Pohle for your reply.