Spe3dfreak

Winter is here and with the extra cold temperatures, before when I start the car it knocks for 2 to 3 seconds then goes quiet. Recently when I start and its cold, it'll knock for the same time , and then I'd hear a rattle or smaller knocks for a short period of time then it goes away. Im not sure if its a bearing problem or if its normal, can someone help? In temps like 40 plus, it starts fine.