Breakdown of Con buen tiempo, el rescate vendría por la mañana.
con
with / just by (+ -ing)
bueno
good
venir
to come
por
for / by / through / in (during a part of the day)
Questions & Answers about Con buen tiempo, el rescate vendría por la mañana.
Why is it vendría instead of "veniría"?
Vendría is the conditional form of venir (to come). Venir has an irregular stem in the conditional tense. Instead of adding the ending to the full infinitive, you use the special stem vendr- and add the normal conditional ending -ía.
Why are we using the conditional vendría here instead of the future tense vendrá?
The conditional is used here because the rescue coming is a hypothetical situation that depends on a specific condition being met: having good weather. If the speaker were stating a guaranteed fact, they would use the future tense vendrá (will come).
Why does the sentence use buen tiempo instead of bueno tiempo?
Why use por in por la mañana to mean "in the morning"?
In Spain, por is the standard preposition used with parts of the day (morning, afternoon, evening) when you are talking generally and not mentioning a specific hour. If you included a specific time, like "at eight in the morning", you would switch to de, as in a las ocho de la mañana.