The Curly Girl's Guide to Dew Points, Humectants, & Humidity

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curly hair and dew points, humidity, humectants, and weather styling

In this post, I break down dew points, humectants, emollients, and humidity so that you can confidently style your wavy and curly hair according to the weather. No more wasting time and product just to step outside and have it all fall apart.

After following the curly girl method for several years, I’ve got the basics down and learned how to work with the weather. Luckily, I live somewhere with pretty consistent temps and dew points year-round, so I don’t have to switch up my products for the seasons. I just need to make sure it’s not full-on raining, because then I definitely reach for a hard hold gel and usually leave some of the cast.

What is Humidity and Why It Matters

Ah, humidity, the nemesis of wavy and curly hair. Having lived most of my life in Miami, I’ve learned to check the weather before I even think about washing my hair.

Humidity is the amount of water vapor in the atmosphere, measured as a percentage. When it’s raining, it’s 100%. When the air is dry, it’s much lower. Most weather apps will include this percentage.

According to curl chemist Tonya McKay, “Hair exposed to very dry air without protection can lose its moisture, develop an unpleasant texture and become unruly, flyaway, and frizzy… Conversely, unprotected exposure to excessive moisture and humidity can swell the hair cortex, raising the cuticle scales and creating coarse, frizzy texture.

In high humidity (around 90%+), curls frizz and lose shape quickly. McKay also says, “This can cause curly hair to swell so much that cuticles are raised, making the surface very rough. These cuticles can tangle with others and create a huge, knotted mess that’s prone to breakage.”

So yeah, humidity usually causes chaos, but you can prep your hair to handle it.

Styled with a hard hold gel for the high humidity and dew point.

What is Dew Point?

Humidity gets all the attention, but the dew point is actually more helpful when it comes to styling curly hair.

Dew point is the temperature at which the air becomes saturated and water vapor starts to condense. It tells us how much moisture is in the air at a given time, and that moisture can absolutely impact your curls.

Here’s why it matters:

You can have 90% humidity in 35°F (2°C) weather and your hair might be totally fine.
But 60% humidity in 70°F (21°C) weather can lead to big frizz.

That’s because warmer air holds more water vapor. So even at a lower humidity, if the dew point is high, your curls can swell and frizz. The higher the dew point, the more moisture your hair will absorb from the air.

My curly hair after a humid day with a high dew point.

Understanding Humectants and Emollients

Before we get into what to use in different weather conditions, let’s talk about ingredients, specifically humectants and emollients.

Humectants

Humectants are moisturizing ingredients that attract water from the air or your hair.

In high dew points, they pull water from the air into your hair, causing swelling, frizz, and tangles.

In low dew points, they can pull water out of your hair, leading to dryness, flyaways, and breakage.

Some common humectants:

Glycerin
Agave nectar
Honey
Sorbitol
Hyaluronic acid
Glucose, fructose
Hydrolyzed proteins (collagen, keratin, silk, elastin)
Propylene glycol

Film-Forming Humectants

These create a flexible film around your hair to help retain moisture and reduce frizz. These tend to be safer in low or high dew points.

Flaxseed
Okra
Aloe vera
Marshmallow root
Slippery elm
Pectin
Guar gum
Hydroxyethylcellulose
Panthenol
Hydroxypropyltrimonium honey

Emollients & Anti-Humectants

Emollients are hydrophobic (water-repelling) ingredients that help seal the hair, reduce frizz, and prevent moisture from escaping. Many plant oils fall into this category.

Anti-humectants work to block or repel excess moisture in the air. These are great for high humidity.

Some examples:

Argan oil
Grapeseed oil
Jojoba oil
Shea butter
Mango or cocoa butter
Olive oil
Avocado oil
Emulsifying wax
PEG-8 beeswax
C12-15 alkyl benzoate

Be aware: some can cause buildup or be too heavy for fine or low-density hair.

Emollients & Anti-Humectants

Emollients are usually hydrophobic oils that act as anti-humectants and seal the hair, like plant oils. Anti-humectants do not attract and in many cases repel water. These have traditionally been silicones, but many other ingredients function similarly to silicones.

Note that emollients can cause buildup or be too heavy for certain hair types. Check out my free Weather Styling Guide for more detailed info.

Some common emollients include:

Argan oil
C12-15 alkyl benzoate
Grapeseed oil
Mango butter
Sunflower oil
Cetyl esters
Cocoa butter
Coconut oil
Jojoba oil
shea butter
avocado oil
olive oil
emulsifying wax
peg 8 beeswax

Humidity Resistant Ingredients

If you live somewhere humid, you’ll want to look for products with humidity-resistant ingredients, especially in your gel or final styler. These help your hair tolerate excess moisture.

Humidity resistant ingredients include:

Polyquaternium-4, -10, -11, -69
Polyamide-1
PVA/VP Copolymer
VP/DMAPA Acrylates Copolymer
Polyacrylate-2 Crosspolymer

You’ll usually find these in strong hold stylers. Just make sure to clarify regularly, because many do build up on the hair.

The photo below shows the ingredients list of the Giovanni LA Hold gel which is a hard hold gel that works well in high humidity and dew points. You can see the red is a humidity resistant ingredient and it’s high on the list in the second place. The black are film forming humectants, and the blue are emollients.