Noise pollution due to fire crackers during Diwali festival has been identifies as one of the major noise pollution problems in the country. It is therefore necessary to conduct noise level monitoring during this period of understand the level of noise pollution. Maharashtra Pollution Control Board has conducted an extensive noise monitoring study in 12 major cities of Maharastra during Diwali festival, 2011. This report contains the methodology and observations made during the study. This document has also summarized the ambient noise levels in different cities during Diwali festival for last 3 years.