Q: Can I break my fast after having intended to fast the day due of unforseen travel?
A: If a resident intends to fast a day in Ramadan but then travels during the day, whether by choice or necessity, he is permitted to break his fast.
However, this applies only once he has left the inhabited area of his town or village, as he is not considered a traveler before that.
That said, the preferable course of action for someone who begins fasting and then travels during the day is to complete the fast to avoid scholarly disagreement on the matter.
Source: Sharh al-Muntaha