Ambiguity, defined as the uncertainty in probability distribution of asset prices resulting from misinterpretation of lack of information, is a current feature of financial assets. There are few empirical studies of ambiguity in financial and commodity futures markets. We define an ambiguity measure of corn and coffee futures daily prices, using the VAR framework to evaluate the autoregressive and cross-impact of the ambiguity and log-returns. Results show that the ambiguity in corn futures prices illustrates a higher impact compared with coffee futures prices, with a possible explanation being the action of non-commercial traders. The knowledge of the ambiguity measure in commodity futures markets can be applied to enhance production, storage, trading and hedging decisions.