Background: The Mediterranean basin, particularly the North African region, is one of the most sensitive regions to climate change. The reproductive performance of dairy cows is negatively affected by heat stress, commonly evaluated by the temperature-humidity index (THI). Purpose: The objective of this study is to evaluate the relationship between the success level of Artificial Insemination (AI) and the fertility of dairy cattle according to the climatic conditions of two localities with different Mediterranean bioclimatic data: Annaba and Ghardaïa. The first is a littoral city located at the extreme northeast of Algeria and the second is a septentrional Sahara located at the south center of the country with extreme arid conditions. Methods: Data regarding the timing of the initial artificial insemination, subsequent inseminations, pregnancy diagnosis, and the duration of the reproductive period were gathered for 1241 instances of artificial insemination conducted throughout the 2020s. The relationship between conception risk (CR), reproductive period (RP), and fertility index (FI) with the temperature-humidity index (THI) on the day of artificial insemination was examined. Results: According to the logistic regression model, we noted a negative effect of THI levels on the success of insemination. The increase in THI is associated with a low probability of AI success (B = −,057, P < 0.001). The odds ratio result of THI (0.94) also indicates that this factor represents a potential effect in reducing the rate of fertilizing inseminations. The results also showed that the rate of non-fertilizing AI when the THI > 70 is significantly higher than the non-fertilization rate when the THI < 70 (69.7% and 53.1%, respectively). Fertiliz-ing inseminations are higher when THI < 70 thanwhen THI > 70 (46.9%; 30.3%). The total fertility index of animals in the Annaba region is 8.71 compared to that of animals from Ghardaïa 3.57 (4.17 on average). Final-ly, the reproduction period is significantly different according to the THI of the first AI with low levels (45 to 48 days) when the THI <70 and 70-80 (P > 0.05) and 90 days when the THI >80 (P < 0.05). Conclusion: This study highlights the harmful impact of climatic conditions on the fertility of dairy cattle breeding and underlines the need to find solutions to mitigate this impact by acting particularly on the welfare of dairy cows.