During times of high customer demand, fares may increase. Surge pricing is specific to the vehicle option as well as the location of both you and your customer.
If you drive through multiple surge areas while waiting for a trip, you'll earn the highest surge amount on your next trip. And if a customer requests from a different surge area than the one you're in, you'll earn the higher of the 2 amounts.
You can zoom in to colored areas of your app's city map to see additional surge amounts that can be earned.