Masterton – current water temperature and swimming conditions
This page provides information about the current water temperature at Masterton in Wellington 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 Ruamāhanga River at Masterton today is 9°C.
Water Temperature in Ruamāhanga River at Masterton: 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 Masterton 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 Masterton will be 10.0°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 |
|---|---|---|---|
| Aug 19 | 13.3°C | 10.1°C | |
| Aug 20 | 13.0°C | 10.1°C | |
| Aug 21 | 13.1°C | 10.1°C | |
| Aug 22 | 13.3°C | 10.1°C | |
| Aug 23 | 13.4°C | 10.1°C | |
| Aug 24 | 13.8°C | 10.1°C | |
| Aug 25 | 9.1°C | 10.1°C | |
| Aug 26 | 9.1°C | 10.1°C | |
| Aug 27 | 9.1°C | 10.1°C | 9.1°C |
| Aug 28 | 10.1°C | 9.2°C | |
| Aug 29 | 10.1°C | 9.4°C | |
| Aug 30 | 10.1°C | 9.5°C | |
| Aug 31 | 10.1°C | 9.6°C | |
| Sep 1 | 10.1°C | 9.7°C | |
| Sep 2 | 10.1°C | 9.9°C | |
| Sep 3 | 10.1°C | 10.0°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 | 15°C | 20°C | 25°C |
| February | 14°C | 20°C | 25°C |
| March | 12°C | 18°C | 23°C |
| April | 9°C | 14°C | 19°C |
| May | 7°C | 11°C | 15°C |
| June | 6°C | 10°C | 14°C |
| July | 5°C | 8°C | 11°C |
| August | 6°C | 10°C | 13°C |
| September | 6°C | 12°C | 17°C |
| October | 7°C | 13°C | 18°C |
| November | 9°C | 16°C | 23°C |
| December | 11°C | 17°C | 22°C |
Masterton: Weather Forecast
August 28
August 29
August 30
August 31
September 1
Location & Local Information
Masterton, located in the Wairarapa of the Wellington Region, sits close to the middle reaches of the Ruamāhanga River. In this lowland section, water temperatures reflect seasonal air conditions rather than alpine snowmelt. During winter, the river near Masterton is generally cool, with temperatures around 8–12°C. In spring, readings typically rise to between 12 and 16°C as days become milder. Over summer, especially in January and February, calmer pools and wider stretches can warm to approximately 18–23°C on settled, sunny days. By autumn, temperatures usually ease back to around 13–17°C. Heavy rainfall in the Tararua Ranges can temporarily lower temperatures and increase river flow.
Swimming Conditions
Swimming is allowed in suitable parts of the Ruamāhanga River near Masterton, and locals often visit established swimming spots during the warmer months. The most comfortable conditions are generally in mid to late summer when water temperatures approach or exceed 18°C and river levels are steady. However, swimmers should be aware of changing depths, submerged debris and moderate currents in some sections. It is advisable to avoid entering the river after significant rainfall, when flows can rise quickly and water clarity may decrease. Checking regional water quality information before swimming is recommended to ensure safe conditions.