At the heart of it, it’s all a matter of climate and seasons. The white uniform is better tailored to warmer temperatures while the blue one to colder places. In the United States Navy this is called a service dress and can be or either colors. The local Naval District defines each year the date of the uniform switch. Some exceptions apply, like the Navy region of Hawaii and Joint Region Marianas where the white service dress remains the norm all year-round.
When is it normal to wear the blue uniform?
The blue service dress is usually worn on colder months or latitudes, however, it can also be worn all year-round or on official occasions. The switch generally occurs around October/November. The material is generally wool which fits nicely with colder weather.
When is it normal to wear the white uniform?
The white service dress is reserved for summer or tropical zones and usually made of polyester.