Do Rash Guards Keep You Warm?

man snorkeling with turtle
Photo by Anton Avanzato from Pexels

Rash guards or skin-suits have now made their way in the diving community and became an essential part of a diver’s gear. Rash guards are not to be confused with a wetsuit where the main purpose is to keep you warm. A rash guard’s most basic purpose is to serve as a barrier between the elements and your skin (like a suit for your skin). Or as a protection against some stinging organisms in the water. So, do rash guards keep you warm? This will be dependent on the style and model of your rash vest or rash guard. With so many different materials and fits, we will also look at how and when to wear these “rashies.”

Here is a summary of the article. Feel free to skip to a section.

Do Rash Guards Keep You Warm?

This question brings a lot of debate as there are many factors to consider. The type of material for your rash guard will greatly impact this. Many of the larger brands now have fleece material or thermal rash guards, which are comfortable and will certainly keep you slightly warmer than without wearing one. However, it will not replace a properly fitting wetsuit.

A typical rash guard worn alone, made of spandex, nylon or polyester will not provide a lot of warmth. This is because it is not thick or strong enough to work like a wetsuit, which keeps a layer of warm water close to the skin. However, a rash guard under a wetsuit can provide an extra layer that helps trap that warm water.

Read more about how wetsuits keep you warm in our Ultimate Wetsuit Guide.

A dry rash guard is great at keeping you warm when you have finished a dive. This is because it will help dry your skin quicker, making you feel warmer. Some rash guards can also be used as a wind barrier. This stops the cold air from chilling your skin, making you feel warmer too!

Are Rash Guards Necessary?

The term rash guard or ‘rashie’ is mainly used as a reference to the protective shirt that can have either short or long sleeves. It can also be applied to the protective leggings, which can be short or long, and made of the same material for the same purpose.

Rash vests or rash guards are fitted waterwear made of spandex, nylon, polyester or even a luxurious fleece! Its purpose is to be used during water sports as additional protection against abrasion from the constant rubbing of a wetsuit or BCD strap against your skin – especially under the arms or around the neck. A rash guard will also provide great protection from the elements, such as the harmful UV sun rays, and can also be used as an added insulation layer.

Find out What to Wear under a Rash Guard.

Do Rash Guards Prevent Sunburn?

Rash guards are an effective barrier from the harmful UV sun rays and your skin. It can prevent sunburn but this will depend on the quality of your rash guard. A branded and tested rash guard will likely have a UV protection rating. This means the material has been made with specific fibers and woven in a particular method to block the sun. Some materials even have a UV-deflecting coating which is also effective. Similar to the SPF rating in sunscreen, the higher the rating, the more effective the rash guard is in blocking out the UV rays.

Watch out for low-quality rash guards that may not be very effective in preventing sunburn. This is because the fibers of the material may be weak or separated which does not provide ample cover over your skin. The most effective way to prevent sunburn is to use a reef-safe sunscreen under your rash guard and allowing at least 30 minutes before heading into the water, to allow the sunscreen to absorb into your skin.

Read more: What to wear scuba diving in warm water?

Do Rash Guards Protect from Jellyfish?

Yes! Rash guards are a great barrier to protect you from stinging organisms such as jellyfish. It is also very useful to protect you from floating sea-lice that can irritate your skin. The rash guard, while thin and light, can be very effective. This is because jellyfish tentacles, sea-lice, anemone, etc. only sting through light touch. They do they purposely piece the skin such as an urchin spike or a scorpionfish spike, which a rash guard will not protect you from.

Remember, jellyfish are not trying to sting you. They just float where the current takes them but you should still try to avoid them even when wearing a rash guard.

When Should I Wear a Rash Guard?

As a scuba diver, you can layer a rash guard under your wetsuit to limit the amount of water going into your wetsuit. Or you can wear a rash guard by itself when the water is warm. In this case, it will protect you against sharp rocks, treacherous fire corals and stingy jellyfish or organisms when you dive.

Rash guards for snorkeling are ideal, as most likely the water temperature will be higher in shallower waters, eliminating the need for a wetsuit. This is because generally the sun will more efficiently heat the first few layers of water and be warmer than deeper waters. A rash guard will be ideal in these conditions, while also protecting you from the UV sun rays and any stinging organisms in the water.

Stylish Rash Guard next to the swimming pool. Do rash guards keep you warm?
This stylish rash guard is perfect for warm water or even layered up under a wetsuit.

Will a Rash Guard Keep You Warm All Day?

You will have more energy and fat cells at the start of your day. However, after a few dives, you will feel more tired and colder. This means that the rash guard that kept you warm at the start of the day may not be enough after a few dives.

Pro Tip: Have 2 rash guards; one to wear during a dive while the other one is drying in the sun. Then switch it around for the next dive!

Do I Need a Rash Guard?

Everyone will have different responses to the water temperature and have a different definition of being cold or warm. This is because some people will be more sensitive to cold than others, and this is generally due to the amount of body fat you have.

Fat cells release energy when they sense the cold, which in turn, keeps you warm. If you have less body fat, then you will lose insulation and be more susceptible to the cold.

The decision of wearing a rash guard will depend on your sensation of the moment. If the water feels a bit too cold for a 3mm wet suit, and you didn’t bring your 5mm one, then wearing a rash guard under your 3mm wet suit might give you the extra comfort you seek to fully enjoy your dive.

Read More: What Do Women Wear Under Wetsuits?

Are Rash Guards Supposed to be Tight?

Rash guards can be short or long, made of one piece or two, and have a tight fit or not. There is no “correct way” to wear a rash guard. How should a rash guard fit will depend on each person’s expectations and sense of comfort. Some people prefer their rashie to fit tight and directly on the skin, while others may prefer a loose fit allowing for more flexibility.

A tighter fit will be more streamlined and not catch on anything. This is ideal for surfers or divers who want to create less drag and resistance in the water. A rash guard that fits close to the skin is also perfect for people who want to keep warm and wear it under a wetsuit.

A looser fit is great for paddle-boarders or snorkelers who are not concerned with being stream-lined. If you are planning an all-day excursion then this will be more comfortable.

Finding the right rash guard for you.

Here are some general guidelines to consider choosing a rash guard for your next dive:

  • You want to be protected as much as possible, so long sleeves and long legs might be more useful.
  • Separate vest and leggings will be easier to put on and take off and allow you more flexibility.
  • A tight fit will be worn more easily under a wet suit and will reduce chafing.
  • A thermal rash guard will be warmer but may take longer to dry.
  • Take also a close look at the seams, and make sure that there is no risk of chafing: you want your rash guard to protect you, not to cause irritations!
  • You may also need to consider if you plan on wearing your rash guard in a swimming pool and choose a material that is chlorine resistant.

Once you decided which fit is the best for you, you will need to pay attention to the quality of the material, as you do not want your new rash guard to be worn out after your first dive. 

snorkeling woman underwater
Photo by John Cahil Rom from Pexels

In conclusion, rash guards are very useful for those who enjoy water sports. By being so versatile; surfers, snorkelers, paddle-boarders, and scuba divers will usually have a rash guard or two in their wardrobe, ready for the water and the sun! As technology has increased, we are now seeing different types of rash guards for various uses. From being worn as a UV layer from the sun to providing extra thermal protection and protecting you from jellyfish stings. So, do rash guards keep you warm? Yes, it can to an extent. It will not provide the warmth of a properly fitted wetsuit or drysuit. But a rash guard can make a difference when used as an extra layer, or if choosing a thicker material version.

Emma was initially terrified of the deep ocean but dived right into scuba diving years ago and hasn't looked back since! After completing her PADI DiveMaster certification and with a Bachelor of Communications (Media) background in film-making, Emma started her scuba career as an Underwater Videographer before becoming a full-time PADI Master Scuba Diver Trainer. She taught and certified hundreds of PADI scuba divers as Open Water Divers, Rescue Divers, Deep Specialty Divers, Dive Masters and more, and then managed several Dive Centres. Her favourite fish (which is also tattooed on her arm) is the Barracuda!