Clarence River – current water temperature and swimming conditions
This page provides information about the current water temperature at Clarence River in Marlborough 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 Clarence River today is 10°C.
Water Temperature in Clarence River: Daily Trends, Historical Records, and Forecast
❌ River water below 10°C is very cold and generally unsuitable for swimming for most people. Even on a warm day, rivers at this temperature can quickly cause cold shock and numbness due to flowing water and shaded banks. Swimming is usually limited to brief cold dips or experienced cold-water swimmers. Overcast weather or cool air temperatures make river swimming especially uncomfortable and potentially unsafe.
Water Temperature Over the Last 30 Days
Water temperatures in Clarence 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 Clarence River will be 8.1°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 | 11.6°C | 7.8°C | |
| May 7 | 11.6°C | 7.8°C | |
| May 8 | 12.5°C | 7.8°C | |
| May 9 | 12.5°C | 7.8°C | |
| May 10 | 12.1°C | 7.8°C | |
| May 11 | 12.1°C | 7.8°C | |
| May 12 | 11.8°C | 7.8°C | |
| May 13 | 10.6°C | 7.8°C | |
| May 14 | 10.0°C | 7.8°C | 10.0°C |
| May 15 | 7.8°C | 9.7°C | |
| May 16 | 7.8°C | 9.5°C | |
| May 17 | 7.8°C | 9.2°C | |
| May 18 | 7.8°C | 8.9°C | |
| May 19 | 7.8°C | 8.6°C | |
| May 20 | 7.8°C | 8.4°C | |
| May 21 | 7.8°C | 8.1°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 | 6°C | 12°C | 17°C |
| February | 8°C | 12°C | 15°C |
| March | 7°C | 11°C | 14°C |
| April | 4°C | 12°C | 19°C |
| May | 3°C | 7°C | 11°C |
| June | 1°C | 5°C | 9°C |
| July | 0°C | 4°C | 8°C |
| August | 1°C | 5°C | 8°C |
| September | 2°C | 7°C | 11°C |
| October | 3°C | 7°C | 10°C |
| November | 5°C | 9°C | 13°C |
| December | 6°C | 10°C | 14°C |
Clarence River: Weather Forecast
May 15
May 16
May 17
May 18
May 19
Location & Local Information
Source Clarence Pass • location Spenser Mountains • coordinates 42°6′14″S 172°42′58″E Mouth Pacific Ocean • location Clarence • coordinates 42°10′S 173°57′E • elevation Sea level Length 209 km (130 mi)
The Clarence River / Waiau Toa flows from the Southern Alps to the Pacific Ocean, cutting through a wide, braided valley between Marlborough and Canterbury. Its water temperature is strongly influenced by alpine sources, snowmelt, and open, windswept terrain. In summer, the river usually reaches around 14–18 °C, which feels cool but refreshing on warm days. During spring and autumn, temperatures typically sit between 9–14 °C. In winter, the water becomes very cold, often around 5–8 °C, reflecting low air temperatures and meltwater from higher elevations.
Swimming Conditions
Swimming in the Clarence River / Waiau Toa is allowed, but it is generally limited to summer and to carefully chosen locations. The river is wide and powerful, with fast currents, braided channels, and sudden depth changes that can make swimming hazardous outside calm side channels or shallow edges. When conditions are settled and flows are low, locals and visitors do swim briefly in sheltered areas, usually for short periods due to the cool water. After rain, river levels can rise quickly and clarity can drop, making swimming unsuitable. Outside the summer months, cold temperatures and strong flow mean swimming is uncommon. Overall, the Clarence River offers refreshing but cool summer swimming opportunities for confident swimmers in suitable spots, while for most of the year it is better appreciated for its scale, landscape, and remote character rather than regular water use.