Read this expecting an easier life and you will misread it badly.
The tree is planted by water and sends out roots by the stream. Then the passage says what happens next. Heat comes. A year of drought comes. Both are assumed.
What changes is not the weather. It is that the leaves stay green and the fruit keeps arriving, because the water source was never the rainfall in the first place.
That is the whole claim. Faith does not exempt you from a hard year. It changes what your hard year is drawing on. People who look unreasonably steady in a bad season are usually not stronger. They are just rooted somewhere the weather does not reach.
And roots take time. Nobody grows them during the drought. They are grown in ordinary conditions, quietly, in the months when nothing appears to be happening and it feels like nothing is.