A crowd of up to 100,000 is expected to gather in Hagley Park North for tonight's Christmas in the Park.
It will be the 20th concert since the event began in 1994.
Christmas in the Park publicist Deborah Delaney said it was "hard to gauge" how many people would turn up, but on a good night 100,000 could attend.
The MetService forecast is for a "few showers", with a southerly change and a chance of hail and thunder.
A representative for the event assured residents the concert would go ahead by tweeting: "We are still on for tonight!".
"Bring extra blankets, a rain coat and be ready for a great night!"
This year's free concert, featuring a record number of performers, will raise funds for Surf Life Saving New Zealand.
Participants include X Factor winner Jackie Thomas and Christchurch band Moorhouse.
The show, which starts at 7.30pm, will end with a fireworks finale about 10.15pm.
Highlights from the event will be shown on TV3 on December 15.
- The Press
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