Selwyn River – current water temperature and swimming conditions
This page provides information about the current water temperature at Selwyn River in Canterbury Region. Here you can view recent temperature trends on a 30-day chart, check typical monthly water temperature ranges, and compare today’s reading with historical averages for this date. A 7-day water temperature forecast, local weather conditions, and an overview of swimming suitability are also included.
Current Water Temperature
The water temperature in Selwyn River today is 11°C.
Water Temperature in Selwyn River: Daily Trends, Historical Records, and Forecast
⚠️ River water between 10 and 15°C is cold but manageable for short swims, especially on sunny days with warm air temperatures. The moving nature of a river can make the water feel colder than the actual reading, particularly in shaded or deeper sections. Casual swimming is usually brief, with wetsuits often preferred. Windy or cool weather can significantly reduce comfort, even when the air temperature is mild.
Water Temperature Over the Last 30 Days
Water temperatures in Selwyn River have been gradually cooling over the past month, with a further drop recorded during the last week.
According to our forecast, the water temperature in Selwyn River will be 9.8°C in the next 7 days. See the table below for daily data for the upcoming week.
Table of Daily Water Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| May 6 | 11.5°C | 9.6°C | |
| May 7 | 11.5°C | 9.6°C | |
| May 8 | 13.2°C | 9.6°C | |
| May 9 | 13.2°C | 9.6°C | |
| May 10 | 13.2°C | 9.6°C | |
| May 11 | 13.2°C | 9.6°C | |
| May 12 | 13.2°C | 9.6°C | |
| May 13 | 11.9°C | 9.6°C | |
| May 14 | 11.3°C | 9.6°C | 11.3°C |
| May 15 | 9.6°C | 11.1°C | |
| May 16 | 9.6°C | 10.9°C | |
| May 17 | 9.6°C | 10.7°C | |
| May 18 | 9.6°C | 10.5°C | |
| May 19 | 9.6°C | 10.2°C | |
| May 20 | 9.6°C | 10.0°C | |
| May 21 | 9.6°C | 9.8°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual river water temperatures may vary by several degrees from the reported values, particularly after heavy rainfall or periods of changing weather. Rainfall, river flow rates, and runoff from cooler upstream areas can significantly affect water temperature, especially in flowing sections and shaded stretches. Air temperature and cloud cover also play an important role, with warm, sunny conditions helping rivers warm up more quickly. As a result, noticeable temperature differences can occur along the same river.
Our forecast is based on a proprietary mathematical model that takes into account real-time river temperature changes, historical data, seasonal patterns, river flow conditions, recent rainfall, and local air temperature. We also factor in broader weather conditions specific to each region of New Zealand to improve accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Today | Yesterday | A Week Ago |
|---|---|---|---|
| January | 14°C | 16°C | 18°C |
| February | 9°C | 14°C | 19°C |
| March | 12°C | 15°C | 18°C |
| April | 8°C | 13°C | 17°C |
| May | 6°C | 9°C | 11°C |
| June | 3°C | 7°C | 10°C |
| July | 3°C | 7°C | 10°C |
| August | 3°C | 6°C | 9°C |
| September | 5°C | 9°C | 12°C |
| October | 8°C | 12°C | 15°C |
| November | 10°C | 14°C | 18°C |
| December | 13°C | 15°C | 16°C |
Selwyn River: Weather Forecast
May 15
May 16
May 17
May 18
May 19
Location & Local Information
Source: • location Southern Alps Mouth: • location Lake Ellesmere / Te Waihora Length 80 km
The Selwyn River, also known as the Waikirikiri, flows across the Canterbury Plains from the foothills towards Te Waihora/Lake Ellesmere. Unlike alpine-fed rivers, the Selwyn is spring-fed in many sections and can vary significantly in flow through the year. Water temperatures reflect this lowland setting. In winter, temperatures are generally around 7–11°C. During spring, they typically rise to between 11 and 15°C. In summer, especially in deeper pools and flowing sections that remain connected, water temperatures can reach approximately 16–22°C on hot Canterbury days. By autumn, temperatures usually ease back to around 10–16°C. Extended dry periods may reduce flow in some reaches, which can influence both temperature and water quality.
Swimming Conditions
Swimming is allowed in parts of the Selwyn River when there is sufficient flow, and some sections are used recreationally during the warmer months. The most comfortable conditions are usually in mid to late summer when temperatures approach or exceed 18°C and the river is flowing steadily. However, swimmers should be aware that the Selwyn can have variable depths, soft riverbeds and occasional strong currents in narrower sections. Water quality can also change after heavy rain or during low-flow periods, so checking regional updates before swimming is recommended to ensure safe conditions.