The cloud point is the temperature at which wax crystals first become visible in diesel fuel, giving it a cloudy appearance. It's typically 10-20°F above the CFPP (Cold Filter Plugging Point). When diesel reaches its cloud point, wax crystals begin forming but the fuel can still flow. Below the cloud point, crystals grow larger and can eventually plug filters and fuel lines. Anti-gel additives lower the cloud point to prevent crystal formation.