morning or afternoon swims?

June 8, 2008 6:32 AM

When are the sun's UV rays weaker: from 10am to 11am, or from 5pm to 6pm? (East coast USA, this month.) Beach has strict swimming hours, 10am-6pm. I'm looking for which is the better hour to go swimming -- regularly over the course of June -- in a bathing suit, very-wide-brimmed solid straw hat, and sunglasses, but no sunscreen.
posted by sparrows to Health & Fitness (15 answers total)

If the sun is at zenith at 12, then 5-6 pm. There's a plot linkedhere. The farther north you are, the more attenuated UV becomes as the sun departs from zenith.
posted by a robot made out of meat at 6:43 AM on June 8, 2008

The way you've written your question makes it look like you're going swimming in a hat and sunglasses. Is that the case?

My completely unscientific view says morning, but I'm very probably wrong.
posted by Solomon at 7:15 AM on June 8, 2008

i would imagine the later hour would be better.

can i ask why you will not be availing yourself of sunscreen?
posted by thinkingwoman at 7:32 AM on June 8, 2008

Best answer: With Daylight Savings Time, the sun is at zenith at 1pm. The morning session's end is only two hours' remove from that zenith, while the afternoon starts out four hours from the zenith. SO the afternoon will have fewer rays. However, in the afternoon, the accumulated heat will make for a hotter time; perhaps this will make the water feel even more refreshing.
posted by notsnot at 7:36 AM on June 8, 2008

Yes, why no sunscreen? And, if you can't, for some reason, wear sunscreen, there are t-shirts and the like you can buy that do a good job of blocking UV rays, such as SPF Store.
posted by Taken Outtacontext at 7:55 AM on June 8, 2008

Response by poster: T-shirts don't work well for swimming (hat and glasses work fine), suncreen is expensive.
posted by sparrows at 8:11 AM on June 8, 2008

how do you swim in a hat? i'm confused. are you just going in for dips or actually swimming?

you should be able to get a store-brand sunscreen for not a lot of cash. at least put it on your upper body and face. it's so worth it.
posted by thinkingwoman at 8:32 AM on June 8, 2008

Sunscreen is expensive? Cancer treatments are more so.
posted by Madamina at 8:50 AM on June 8, 2008 [1 favorite]

Response by poster: I am swimming, for an hour, in a huge hat and sunglasses. :) You don't need to put your head in the water to swim if you don't care about efficiency or speed. I just wanted a reality check and notsnot's answer was perfect: even though afternoon feels hotter temperature-wise, it has less UV rays.
posted by sparrows at 8:53 AM on June 8, 2008

Sunscreen is expensive? Cancer treatments are more so.

Actually there is no epidemiological link between melanoma and not wearing sunscreen, believe it or not.

Wikipedia:

" The cause is the exaggerated UV-exposure. It has been shown that sunscreen - while preventing the sunburn - does not protect from melanoma. [18] Many researchers say that sunscreen can even increase the melanoma risk (see Sunscreens and Cancer by Hans R Larsen)."[1]
posted by tachikaze at 10:13 AM on June 8, 2008 [1 favorite]

Weather.com has a map of the current UV index, updated every hour.
posted by magicbus at 10:19 AM on June 8, 2008

I calculated the clear sky solar radiation for today in NC and the morning was about 3.5 times as high as the evening. Of course, the UV radiation may vary somewhat, but in any case, the evening is much better.
posted by ssg at 1:13 PM on June 8, 2008

There is some UV penetration through water. When my aunt was recovering from breast cancer & radiation, they said to stay out of the sun till 4 p.m.
posted by theora55 at 1:57 PM on June 8, 2008

Sunscreen is also pretty toxic to marine life (it's been banned from several marine parks where it was killing coral). There are even some suggestions it may be toxic to your skin.... I wear the zinc stuff and find that it is more expensive initially but cheaper in the long run and doesn't kill everything around me. Just an fyi.

I'd say swim in the evening and work up to more sun exposure. You could consider a triathalon "skin" a super lightweight full body suit (see Sierra Trading Post online for deals on these). It also helps you swim longer because it gives you some buoyancy and keeps you warm.

If you're concerned about sun exposure on your face I'd say go ahead and swim front crawl without the hat and sunglasses, you'll get very minimal sun exposure with your face in the water most of the time.
posted by fshgrl at 2:04 PM on June 8, 2008

Rash guards are good too for warmer places and most come up high on the neck and have full sleeves.
posted by fshgrl at 2:05 PM on June 8, 2008