Smallholder climate resilience in sub-Saharan Africa is limited by low uptake of adaptation technologies due to poor access to climate forecast information services (CFIS). Cross-sectional data from 2,934 farming households in northern Ghana are used to explore econometric drivers of CFIS access and its causal mediation on household food security. Probit marginal effects show that access to agricultural extension, formal literacy, radio ownership, and perceptions of climate stress strongly increase the likelihood of CFIS adoption. However, peripheral upper west and northeast households face severe access deficits due to infrastructure dead zones and ethno-linguistic barriers, respectively. Two-stage causal mediation and generalized structural equation modeling (GSEM) indicate that CFIS access significantly increases dietary diversity by 0.210 units and significantly reduces food insecurity access anxiety by 0.103 units. Agricultural yield is a strong and significant partial mediator, but only 7.8–14.6% of total food security gains are mediated by it. That is, direct risk-buffering channels dominate (about 85.4 to 92.2%); hence, CFIS is primarily an adaptive safety net for off-farm labor reallocation, asset preservation, and consumption smoothing. Policymakers need to move beyond narrow agronomic advice to integrated climate risk management by bundling CFIS with weather-index insurance, local-language interactive voice response platforms, and decentralized extension networks.