In class, the question arose because a student reported that she got the answer wrong on a test because she thought due was always followed by a time. But due when followed by to means caused by. Another synonym for due is attributable according to the Columbia Journalism Review site. The explanation further notes that "due to" is usually preceded by some form of the verb be or words that function like it, that is, linking verbs.
Their examples are:
- "The power failure was due to a lightning strike."
- "Their exhaustion seemed due to the humidity rather than the heat."
Here is a little more about due. Due with prepositions can connect with money and time.
Due to is also used with money.
- Ten dollars for the tickets is due to Mr. Jones.
To return to the original point about due to. When due is used with on or in, it often refers to a time.
- The paper is due on the last day of the month.
- Your answer is due in ten minutes.
Due has several uses beyond pointing to time including causes and money.