Cross-Laminated Timber (CLT) is becoming increasingly popular for mid- and high-rise structures due to its structural and environmental benefits. Despite its advantages, the long-term durability of CLT, especially under wind-driven rain exposure, remains a concern. Hygrothermal simulation is commonly used to assess moisture performance; however, previous studies mainly focused on one-dimensional simulations for wall assemblies. This study investigates the hygrothermal performance of a CLT wall-floor connection under rain penetration loads. A two-dimensional DELPHIN model was developed using anisotropic properties for CLT and validated using experimental data from a field study on CLT wall assemblies in Vancouver. During the test, water was injected into wetting pads placed on the CLT surface to simulate real-world rain penetration. The model’s accuracy was validated by comparing simulated with measured moisture contents (MCs) at both the exterior and interior CLT surfaces, showing good agreement with a mean absolute error (MAE) of 3% at 6 mm from the exterior CLT surface. The validated model was then used to assess a CLT wall-floor connection under extreme moisture reference year conditions, applying 1% of wind-driven rain (WDR) as the moisture load at the exterior surface of the CLT layer according to ASHRAE 160. The results showed slightly lower temperatures at the floor level (maximum difference of 0.4 ℃), higher MC (MAE of 0.32%, maximum difference of 5%), and a higher mold growth index with a maximum difference of 0.1 compared to wall location. The findings indicated that the wall-floor junction is slightly more vulnerable to moisture.