The aim of this study is to accomplish a climatic risk zoning to define the best season to planting rice in thecentral region of Maranhão State. There were used data from the Brazilian Institute of Geography and Statistics;Historical series of precipitation and temperature obtained from the National Water Agency and National Instituteof Meteorology. The agroclimatic risk zoning was accomplished using the SARRAZON program. The climatic riskfor sowing rice was defined as follows: ISNA> 0.65 - Low climatic risk, favorable region to the planting; 0.55<ISNA <0.65 - intermediate region; ISNA <0.55 - High climatic risk, unfavorable region. For the R7 Region insoils with CAD 30 mm, the period ranges from the first ten-day of December to the first ten-day of February. Andfor soils with CAD 40mm, the better planting season is from the third ten-day of November to the third ten-day ofFebruary. For the R9 homogeneous region in soils with CAD of 20 and 30 mm, the results showed since the thirdten-day of November to the second ten-day of January. For soils with CAD 40 mm, the rice sowing ranges from thethird ten-day of November to the third ten-day of January.