Another mother, Rebecca Powell, saw a 2-year-old boy in an Auckland emergency room last weekend who had broken both arms when he quickly jumped off a slide because it was too hot.
Ms Berriman said the problem could be easily fixed if councils installed sun shades.
However, the Hamilton City Council said the high cost of installing the shades was a major barrier.
As well as the six official complaints, the Hamilton City Council had received other feedback via social media about its playgrounds being too hot, with the junior playground at Hamilton Lake in particular attracting criticism.
Parks and open spaces manager Sally Sheedy said the council was investigating several options for installing a robust permanent shade or shade sail at the lake. But she said the cost was estimated to be between $10,000 and $15,000 and the structures were prone to vandalism.
There were no plans to change equipment to make it more heat resistant because the council had been advised there was minimal temperature difference between metal and plastic play equipment.
Auckland Council parks, sport and recreation manager Ian Maxwell said playgrounds heating up in the sun was a reality of outdoor recreation structures.
However, the council looked for products that were more heat resistant and positioned slides so they were out of the direct sun and near existing mature trees or planted new trees.
"The construction of formal shade sails is not considered appropriate for local playgrounds due to the cost," he said.
"We also count on parents and caregivers doing their bit to ensure the chance of children being injured when at playground is minimised. Just as extra care is advised when rainy conditions make play equipment slippery."
He said Auckland Council had received very few complaints regarding playgrounds getting too hot from the sun.
Safe Kids director Ann Weaver said there were playground standards for councils to follow but she did not think it included guidelines around heat resistance materials or shade.
The Cancer Society supported sun shades being mandatory on all public playgrounds. SunSmart school co-ordinator Louise Sandford said: "Not only do those playgrounds get hot but we should be protecting [children] from harmful UV rays."
When slides just aren't a lot of fun
Hamilton mother Dulcie Hooper took her children down to Hamilton Lake as a treat before they went back to school.
But instead of sliding down the playground and using the swings at the junior playground, her two older children Danielle, 7, and Ethan, 6, had to climb around a shaded rock garden because it was the only place where they could escape the relentless sun.
Children had avoided the metal tunnels and slides all Tuesday morning.
The mother-of-three said it was "ridiculous" a toddlers' playground got so hot and questioned why the council did not use slides made from plastic instead of stainless steel and put a sun shade over what was one of Hamilton's most popular playgrounds.
She said it was a struggle to find any well shaded playgrounds in Hamilton and was particularly disappointed three main play areas - Hamilton Lake, Claudelands and Callum Brae - were in direct sunlight.
"What's the point of having outdoor playgrounds for children if they can't use them during the day because they could burn themselves on the equipment?" she said.
"We know we have got to put sunblock on them and hats but it would really be more enjoyable if it was shaded.
"I don't want them burnt."
