The optimal temperature and humidity for archival storage depend on the specific types of documents and materials being preserved. Generally, a temperature range of 65-70°F (18-21°C) and humidity levels between 30-50% relative humidity are considered suitable for most archival materials. However, certain materials may have specific requirements; for example, photographic materials may benefit from lower humidity levels to prevent mold growth, while some organic materials like leather may require slightly higher humidity to prevent desiccation and embrittlement. It's crucial to consult conservation guidelines and material-specific recommendations when establishing storage conditions.