You are only going to be able to do this if someone had done a high resolution/precision survey of the elevation data in the area you are interested in. Given where you live, I suspect you've got less chance than average.

Google do provide API access to their elevation data, but as you've guessed it typically is rough and ready in its precision and accuracy:

https://developers.google.com/maps/documentation/elevation/intro

Here is an example bit of UI using Google's data:

http://www.geocodezip.com/v3_elevation-profile_distance.html

In some parts of the world much better data sets are available:

https://environmentagency.blog.gov.uk/20...risk-knowledge/