Warning as 10 days of sun forecast
Experts are warning Cantabrians to be careful when swimming as reports of serious stomach bugs are up on previous years.
Canterbury medical officer of health Alistair Humphrey said there was a risk of infection when swimming in rivers, pools and spas.
The most common infections were gastro infections such as giardiasis.
Giardiasis is caused by an organism that lives in the digestive tract.
The disease can cause severe stomach cramps and diarrhoea. Symptoms can last for months, often settling only after antibiotic therapy.
"Already this year 20 cases of giardiasis have been reported, compared to 14 for the same time last year," Humphrey said.
"We do know there are giardia cysts in the silt of our local rivers based on an ESR [Environmental Science and Research] report published last year, so it is important to very aware of this when boating or using waterways."
In theory, the illness could be spread in pools and spas by people who were shedding microbes, he said.
To reduce the spread of giardiasis and other illnesses, Humphrey said, it was important people washed and dried themselves properly after swimming in rivers and pools.
"If they have had diarrhoea symptoms they should stay out of pools and spas for at least two weeks after their symptoms have subsided," he said.
The warnings come as a week of high temperatures are likely to see Cantabrians cooling off at the region's beaches and rivers.
MetService is forecasting a weekend of increasingly warm days, with 23 degrees Celsius forecast for tomorrow, 25C on Sunday, rising to 30C by Tuesday. Temperatures are likely to remain in the mid-20s for the rest of next week.
Meterologist Daniel Corbett says the golden weather was because of a "big, fat area of high pressure" building over New Zealand.
"This one will build and it will sit in place," he said today.
"It's like a big mountain of air sitting over New Zealand. That's why the forecast is just looking spectacular."
It was difficult to pick the best spot to be in the country this weekend, he said.
"The high is pretty good and it covers most of the country. Everywhere is going to be good," Corbett said.
"If people want to be up in the mountains tramping, that will be nice. If they want to be out in the boat, that should be nice too.
"It's just perfect weather for the outdoors. Just get out the barbecue or pop the tent on the beach and make the most of it."
However, the warm weather forecast for Canterbury is not because of the northwesterlies that have helped spark damaging scrub fires.
The forecast is notable for a lack of wind, or light northeasterlies.