Is it necessary to wear a sun hat outdoors in 24 degrees?

It depends on the individual's sunscreen needs and sunscreen ability.

Generally speaking, sun hats can provide extra sun protection, especially for scalp and hair. If your hair is short or your scalp is sensitive to sunlight, it may be a good idea to wear a sun hat. In addition, if your job requires working outdoors for a long time, or you often exercise outdoors, wearing a sun hat may be more necessary.

However, if you have used proper sunscreen and won't be exposed to the sun for a long time, wearing a sun hat may not be necessary. In addition, some people may not like wearing hats, or there is no tradition of using hats indoors.