How to determine the latitude of the city on the map?

Question

PHP

A person manually enters a city and I need to get its latitude on the map. Next, you need to determine that the latitude is less than the latitude of the control point on the map. For example, a person entered Voronezh, then I need to find out the latitude is less than the control point on the map or not (for example, this is Tyumen).
How can this be implemented?
Initially, the task is as follows: there are 4 delivery zones. From Moscow to Tyumen, from Tyumen to Vladivostok and 2 more zones. And I need to determine which zone the city falls into.

Answer 1

The Yandex geocoder can do this.