Unification Ministry spokesman Chun Hae-sung told South Korea's Yonhap news agency the aid includes medical kits, food and other emergency supplies for a province along the Chinese border hit by recent flooding.
A Seoul relief group, Good Friends, said at least 32 people were killed and 38 others are still missing following a flash flooding caused by heavy rains.
The Red Cross is Seoul's main channel for humanitarian cooperation with the North.
Chun said so far North Korea hasn't responded to the offer.
If accepted, the aid may help alleviate heightened tensions on the Korean Peninsula since the sinking of a South Korean warship in March.
South Korea has blamed Pyongyang for the incident that killed 46 sailors