Humidity can be one of hair's biggest enemies, and with good reason. All of those water molecules in the humid air disrupt your hair's hydrogen bonds, leaving you with strands that stray from their intended style. Aside from using one of the best products for frizzy hair in humidity (which I'll get into below), there are a few other tricks you'll want to employ to keep humidity at bay.
Most importantly, you'll want to keep your hair as healthy as possible, because when it's dried-out and damaged, it absorbs more moisture from the air, meaning more frizz. In addition to the obvious, like using heat-protectant sprays and regularly applying a deep conditioning hair mask, try to avoid blow drying your hair or drying it with a towel (which raises the hair cuticle). Also, use a brush made with natural bristles to help keep it smooth.
When it comes to products specifically, there are a number of categories dedicated to fighting frizz. While each comes with different instructions (oils should be used on wet hair, from the mid-lengths to ends, and anti-frizz hairsprays on dry hair, etc.), they all have the same end goal: Keeping your style of choice intact. Because of this, many of the key ingredients are the same.
Silicone-based products help to seal the hair cuticle and create a protective barrier against humidity and pollution, but they can weigh hair down if it's on the finer side. Another popular ingredient is a protein like keratin, which is naturally found in hair and helps strengthen it. Then, of course, there are the oils. Not only do oils like argan, avocado, and coconut help protect hair from humidity, but they're also deeply nourishing and can help improve your hair's overall health with their nutrient-rich make up.