Summer safety alert: Beware of rising river levels and unpredictable weather
Before heading to your favorite Canterbury rivers or lakes this summer, check the weather forecasts and river conditions, especially for rainfall in the Southern Alps. Hot, dry nor-west winds often signal heavy rain in alpine headwaters, which can cause rivers to rise quickly — even when conditions look calm downstream.
Key risks to be aware of on Canterbury rivers this summer
Our duty flood controller, Chris Fauth, advises that if you’re spending time around Canterbury’s rivers or lakes, you need to be aware of forecast rain in the headwaters of the Southern Alps.
⚠️Sudden river rises from alpine rainfall
The strong, hot, dry wind of Canterbury’s infamous nor-westers usually means heavy rain in the upper reaches of our alpine rivers such as Waiau Uwha, Hurunui, Waimakariri, Rakaia, Rangitata, Waitaki (and Waitaki Lakes) and Ahuriri.
"It may be a beautiful day in the Waitaki Valley, or out boating on the Rangitata River, yet it could be pouring with rain back in the mountains," Chris said.
"The water has to go somewhere, and the result is usually one to two days of higher flows and changeable river patterns out on the Canterbury plains. Thats why checking the weather forecast and river flows regularly is important. We want people to enjoy their summer and to stay safe," Chris said.
⚠️Rapidly changing braided river channels
At this time of year, braided river channels can shift quickly. Areas that are dry or easy to cross earlier in the day can fill rapidly, turning riverbeds into islands and leaving people or vehicles stranded.
Vehicles are sometimes washed downstream after drivers attempt to cross channels that rise unexpectedly.
⚠️Increased river flows from hydro lake spills
Summer rainfall can also trigger spill flows from hydro lakes into rivers. The southern lakes currently have high water levels, and Meridian Energy has confirmed controlled water releases from Lakes Benmore, Aviemore and Waitaki while inflows remain elevated. Find out how to stay safe while exploring the southern lakes this summer.
Check before you go
Chris says many incidents could be avoided by checking conditions upstream before heading out.
“It can happen so quickly. People aren’t checking weather conditions in the mountains before they head to the river,” said Chris.
Before visiting rivers or lakes, make sure you:
- Check MetService for warning and weather warnings, including conditions in alpine headwaters
- Monitor river flow and rainfall data on our website.
- Follow flood warnings and updates on our Facebook page.
- View current hazards and navigation safety alerts for the Canterbury region