Schedule
Pole position qualifying, generally referred to as "Pole Day," is currently held on a Saturday the weekend before the day of the race. The actual Pole is determined by the fastest 9 cars in the qualifying round running a shootout later in the afternoon. Two days of qualifying are scheduled in total, the Saturday and Sunday before the race.
Springtime rain in the midwest is often a factor, and over the years, many days of qualifying have been delayed, ended early, or completely washed out due to rain. If pole day is rained out, it is moved to the next qualifying day scheduled. This happened most recently in 2006, when the first two days of qualifying were rained out. Pole position qualifying ended up being held on the third day, followed by what remained the fourth and final day.
Read more about this topic: List Of Indianapolis 500 Pole-sitters