Weather in Seoul varies greatly from season to season. Dressing accordingly is a great idea whether you visit during the hot and rainy summer months or the freezing cold winters when it can snow. The best time to visit is in the spring and fall when weather is usually very comfortable and pleasant.
There are no required or specific vaccinations for travel to South Korea, but it is highly recommended that all travels talk with their doctor if they have any questions and be up to date with routine vaccinations, Hepatitis A/B, and Typhoid. Be sure to check with your doctor before traveling to Korea or if you have any questions about your health.
All visitors are required to have a valid passport. Citizens of the United States traveling to South Korea as a tourist are not required to have a tourist visa if they intend to stay in the country for less than 90 days. The total number of days you can stay varies by country. Those wishing to work in Korea will be required to obtain a work visa prior to arrival. Those who need to say for longer can visit an immigration office in South Korea to request an extension.