Concrete pavements are regularly designed for periods of 30 to 50 years and are affected by different weather-related and climatic factors during this period. The current study focuses on the study of the reaction of slab thickness designed for concrete pavements by the 1998 AASHTO Supplement method to each of the climatic factors and grading the Iran’s map based on the influence of the climatic factors of each region on the design of the concrete pavement thickness. This zoning will be effective in estimating the thickness required for concrete pavements in each area as well as in predicting slab-related damage in concrete pavements. To this end, a sample cross-section of Jointed Plain Concrete Pavement (JPCP) (as the most commonly used concrete pavement) was selected for analysis, and the sensitivity of slab thickness obtained by the 1998 AASHTO Supplement design method to each of the climate variables such as air temperature, wind speed and precipitation, was evaluated using the Normal Sensitivity Index and then Iran's climate area was graded using these results. The results showed that in the field of climatic factors, the increase in designed slab thickness in the software is due to increasing temperature, increasing wind speed and decreasing annual precipitation; the average annual share of temperature among these three factors is 87%, the annual average share of wind was 12% and the annual average share of rainfall was 1%. The range of slab thickness variations obtained from baseline conditions in Iran's climatic conditions range from about 11% increases in Bandar Abbas to about 5% decrease in Shahrekord.