Translation of theirs in German

The first link that you provided (http://www.vocabulix.com/conjugation/Spanish-Verbs.html) takes me to the Spanish Verbs Page (Verb Module). This section is an online version of all the conjugated verbs.
The writer describes this situation by putting the persons into a natural environment. On one side there was no shade and there weren't any trees, he says. This description can be interpreted.
We considered staying a little longer in this region but the weather forecast foresaw heavy winds and lots of rain. We therefore decided to move on to our next destination which was the Peninsula Valdes.