Abstract: The conversion of most available hourly rainfall data to 1-minute integration time rain
rate statistic is imperative for accurate estimation of attenuation due to rain employed in the
design of both terrestrial and earth-to-space microwave systems. 2-year rainfall data collected at
Ogbomoso, South-west region of Nigeria, between the periods of 2009 and 2010 was used in the
analysis. Result shows that a power law relationship exists between the equiprobable rain rates of
two different integration times. The regression coefficients a and b obtained are slightly different
from the ITU-R recommendation. The conversion factor obtained at Ogbomoso is lower
compared to Ile-Ife, in the South-west region of the country. The disagreement is attributed to the
effect of global warming hitting the whole universe most especially the tropical regions. This
study also reveals that different conversion factors are required for different locations even
within the same climatic region.