Is the PDO or AMO the climate driver of soil moisture in the Salmon River Basin, Idaho?

• Soil moisture in the SRB is linked to the variations of the PDO and AMO.
• PDO and AMO have less significant impacts on soil moisture in snow-dominated regions.
• PDO produces, with respect to AMO, a stronger correlation with soil moisture.

Current droughts and increasing water demands are straining water resources in the Salmon River Basin (SRB) and are anticipated to continue in the future. As a robust drought indictor, soil moisture plays an important role in characterizing prolonged droughts. The current study investigates the impacts of two oceanic–atmospheric patterns, i.e. the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO), on soil moisture and identify the most complete driver (PDO/AMO) of soil moisture in the SRB. Using wavelet analysis tools, we found that: 1) soil moisture in both Stanley station (a snow-dominated region) and White Bird station (a rain-dominated region) in the SRB are linked to the variations of the PDO and AMO; 2) both the PDO and AMO have less significant impacts on soil moisture in Stanley station; and 3) the PDO produces, with respect to AMO, a stronger correlation with soil moisture in the SRB. Given the importance of the soil moisture to the drought, the results could allow an estimation of drought availability under forecasted oceanic–atmospheric patterns, which will provide useful information for water resources management in the SRB.