Hamilton claimed the pole for Mercedes Saturday with a qualifying lap of 2 minutes, 1.012 seconds at Spa, edging Sebastian Vettel of Red Bull, who crossed the line in 2:1.200.
"I was surprised when I came across line," said Hamilton. "I went wide in turn one, and my dashboard told me I was three seconds down, and then it was four seconds and then six seconds. So I didn't know what was going on, but I kept pushing."
Mercedes and Red Bull caught a break from the weather Saturday. One of the frequent rain showers that move through Belgium's Ardennes slowed down the early qualifiers but the weather cleared before Hamilton and Vettel took their turns on the 4.352-mile, 19-turn course.
The Belgian Grand Prix takes place Sunday.