Hot and sweaty, but no rain: Day one of the Austin City Limits Music Festival in Zilker Park went off without any big hitches and with plenty of music and good vibes.

1. Anticipation built throughout the day for Paul McCartney, one of the biggest headliners the fest has ever had. His 7:45 p.m. set was expected to run more than two hours, with lots of Beatles classics in his recent tour setlists.

2. About 3:30 p.m. Friday, the park started to fill up, and lines for things such as water refill stations got long.

3. Not surprisingly, McCartney got some special love early in the day, with the local elementary school Barton Hills Choir singing the side two suite of "Abbey Road" in their Austin Kiddie Limits set. But David Byrne tipped his hat to another ACL Fest performer in his afternoon set on the American Express stage, covering Janelle Monae's sociopolitical anthem "Hell You Talmbout." Monae plays at 4 p.m. Sunday.

4. Get ready to rock hard. Heavy metal titans Metallica will headline the festival's big stage Saturday night. If you want to preview Sunday's headliner, Travis Scott, tune into "Saturday Night Live"; he's the NBC show's musical guest. Other anticipated Saturday sets: St. Vincent, Residente, Chvrches, Justice and Nelly.

5. Saturday's forecast from the National Weather Service calls for overcast skies with temperatures warming up to about 87 degrees. Rain chances will increase from 30 percent in the daytime to 40 percent at night.