Faba bean (Vicia faba L.) is an important component of cropping systems in cool, arid environments. However, no review has specifically focused on the quantitative sensitivity of physiological processes in faba bean to low temperature and water deficits. The objective of this review was to examine published functional relationships between physiological activity and these environmental variables. Among faba bean genotypes, temperature generally resulted in a consistent linear response in plant ontogeny and leaf area development. By contrast, nitrogen fixation exhibited a sharp threshold response to temperature such that at temperatures below ~13.5–15°C faba bean had virtually no nitrogen fixation activity. This inability to fix nitrogen under cool temperatures is likely to be a major weakness for faba bean in cool-season production systems. Water deficit also had a large impact on the physiology of faba bean. Ontogeny was generally shortened when plants were subjected to drought, resulting in major yield decreases. Genotypic differences within faba bean have been identified for initiation of partial stomata closure at high soil-water content, resulting in possible soil-water conservation in the field. Also, differences among genotypes have been identified in the sensitivity of nitrogen fixation activity to water deficits. Finally, collectively the reviewed functional relationships have been applied to simulation analysis of the geospatial impact of irrigation regimes and of sowing date for faba bean production. These geospatial studies offered insights on options to improve faba bean management.