I was asking that exact same question yesterday
soo... dew points for dummies (that's how I understand it
1) you should check your Frizzforecast, it's on this website, under "Care". You have to type in your location and click your curl pattern. The website will give you the expected temperature for your area for the next couple of dates, the humidity percentage and the dew temperature. Then it will say if you are expected to have happy curls or not the next couple of days, and what sort of products to use to make the best out of it (humectants-antihumectants)
2) Dew points itself:
Dew point temperature can never be higher than normal temperature.
If the dew points are lower than 30, you're having low humidity and your hair curls will probably not be as springy and happy. (but you can help them with products)
If the dewpoints are between 40 and 60, you are expected to have happy curls and you can use a mix of moisture and humectants.
If the dewpoints get higher, you risk more frizz.
You don't really have to watch the humidity percentage because that's relative humidity...
Example: 80% humidity in winter when it's cold, is less humidity than those same 80% humidity in summer when it's hot...
(because it would be that 80% of the outside temperature that gives the dew point)
Did you understand my explanation?
Other curlies who know more about dew points: did I explain it correctly?