The optimal temperature for biogas production typically ranges between 35°C and 40°C (95°F to 104°F) for mesophilic digesters and between 50°C and 55°C (122°F to 131°F) for thermophilic digesters. It is crucial to monitor and maintain the digester's temperature within the recommended range to promote the activity of the microorganisms responsible for the anaerobic digestion process.