The regional climate model (RegCM4) was used to project the maximum and minimum air temperatures (T_max and T_min) of Egypt considering the worst-case scenario: Representative Concentration Pathway 8.5 (RCP8.5). To achieve this goal, the spatial pattern of the simulated T_max and T_min was first examined. After that, the simulated T_max and T_min were bias-corrected in the historical period with respect to station observations using the Linear-Scaling (LS) technique. Finally, the LS was used to correct the two future scenarios. To downscale the RegCM4, the medium resolution of the Earth System Model of the Max Planck Institute (MPI-ESM-MR) was used to provide the lateral boundary condition and sea surface temperature. The results showed that both T_max and T_min exhibit the highest increase in the far-future period (2081–2100) particularly over Western Egypt, the Red Sea, and Upper Egypt (by 4–6 °C). Additionally, the RegCM4 performance is remarkably improved when the LS method is used. Such performance is indicated by a low mean bias in the validation period compared to the evaluation period over majority of stations. Further, the added value of the LS is noted in T_min more than T_max. Therefore, the RegCM4 can be used to project the T_max and T_min using the LS over the location of interest. In addition, using multiple General Circulation Models (GCMs) is necessary to account for uncertainty associated with the atmospheric forcing.

Daily maximum air temperature (TMX) and daily minimum air temperature (TMN) are sensitive to the soil moisture status and land surface parameterization. However, this point has not been addressed in arid regions (e.g., Egypt). To address this issue, four 13-year simulations were conducted within the framework of the regional climate model (RegCM4). The first two considered the soil moisture status (bare soil versus global satellite soil moisture product; ESACCI). The other two considered the sensitivity to the two land surface schemes coupled to the RegCM4: Biosphere Atmosphere Transfer System (BATS) and version 4.5 of the community land model (CLM45). In all simulations, the RegCM4 was downscaled using the Era-Interim reanalysis with 25 km grid spacing. The simulated TMX and TMN were evaluated with respect to the Climate Research Unit (CRU) and station data. The results showed that switching from bare soil to ESACCI has a considerable influence on the simulated TMX and TMN. Compared to the CRU, the CLM45 outperforms the BATS on the coasts of the Mediterranean Sea and Red Sea (in terms of the TMX) and in the inland regions (in terms of the TMN). When compared with the station data, the behavior of the BATS/CLM45 varies with the location and month. Despite the noted biases, the RegCM4 can be recommended for future studies concerning the seasonal forecast or climate change of Egypt when it is configured with the CLM45 land surface model and initialized with the ESACCI satellite product.