Trip-during [possessive-の] weather [topic-は] how was [question-かと] Bill [to-に] asked.
Embeds an indirect question (天気はどうだったか) inside a reporting clause (ビルにたずねた). The quotative と marks the boundary between the question and the asking verb. たずねる (to ask/inquire) is a slightly more formal synonym of 聞く.