Arrowrock Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Arrowrock Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Arrowrock Reservoir today is 19.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| JUN 23 | 19.2°C | 18.2°C | |
| JUN 24 | 19.2°C | 18.2°C | |
| JUN 25 | 19.5°C | 18.2°C | |
| JUN 26 | 19.8°C | 18.2°C | |
| JUN 27 | 20.5°C | 18.2°C | |
| JUN 28 | 21.6°C | 18.2°C | |
| JUN 29 | 19.9°C | 18.2°C | |
| JUN 30 | 19.5°C | 18.2°C | |
| JUL 1 | 22.0°C | 19.6°C | |
| JUL 2 | 22.0°C | 19.8°C | |
| JUL 3 | 22.0°C | 19.9°C | |
| JUL 4 | 22.0°C | 20.0°C | |
| JUL 5 | 22.0°C | 20.1°C | |
| JUL 6 | 22.0°C | 20.3°C | |
| JUL 7 | 22.0°C | 20.4°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 0°C | 2°C | 5°C |
| February | 1°C | 3°C | 6°C |
| March | 2°C | 6°C | 10°C |
| April | 4°C | 9°C | 14°C |
| May | 10°C | 15°C | 20°C |
| June | 15°C | 18°C | 22°C |
| July | 18°C | 22°C | 26°C |
| August | 19°C | 22°C | 25°C |
| September | 18°C | 21°C | 24°C |
| October | 12°C | 17°C | 22°C |
| November | 5°C | 10°C | 13°C |
| December | 0°C | 3°C | 7°C |
Arrowrock Reservoir: Water Temperature by Location
Arrowrock Reservoir: Weather Forecast
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Location & Local Information
Arrowrock Reservoir is a deep, river‑fed impoundment, so water temperatures stay cooler than many shallow lakes. Seasonal surface temperatures commonly run from near freezing in winter — about 32–40°F (0–4°C) — to spring values roughly 40–55°F (4–13°C). In summer the warmest surface readings typically reach about 60–70°F (16–21°C) on sunny days, while fall temperatures usually fall back into the 45–60°F (7–16°C) range. Because the reservoir is fed by snowmelt and has substantial depth, even summer surface temperatures can feel brisk compared with lowland swimming lakes, and temperatures drop quickly with depth.
Swimming is generally permitted in recreation areas at Arrowrock, but conditions and local rules determine where it is safe. The reservoir’s cold water, steep banks, strong currents near the dam and inlet channels, boat traffic, and sudden changes from releases mean that swimmers face hazards even when the surface seems warm. Management or posted signs may close or limit access at times for safety or operational reasons, so visitors should follow on‑site guidance, wear flotation if appropriate, and be aware that water temperatures can induce cold‑water shock and fatigue much more quickly than in warmer lakes.