Temperature:

Your Favorite Locations:

Your favorites list is empty.

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.

Arrowrock Reservoir, United States
Arrowrock Reservoir, United States © By Bureau of Reclamation, CC BY-SA 2.0

Current Water Temperature

26.1°C
Today
26.2°C
Yesterday
25.0°C
A Week Ago
Get instant access to real-time water temperatures for this and all other locations with our iOS and Android apps.

Water Temperature in Arrowrock Reservoir today is 26.1°C.

Water Temperature: Daily Trends, Historical Records, and Forecast

✅ As of today, the minimum water temperature ranges from 79°F (26°C) to 82°F (28°C). This is very warm water, allowing for extended stays without any discomfort. Swimming in these conditions will be particularly enjoyable, making it the ideal temperature range for those who want to relax in the sea. Additionally, water in this temperature range is suitable for children and elderly people, as it is comfortable for prolonged stays. 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

From June 20 to July 21

Table of Daily Sea Temperature Data

Date Current Average Forecast
JUL 1425.0°C22.6°C
JUL 1527.1°C22.6°C
JUL 1627.2°C22.6°C
JUL 1727.2°C22.6°C
JUL 1826.5°C22.6°C
JUL 1926.2°C22.6°C
JUL 2026.2°C22.6°C
JUL 2126.2°C22.6°C
JUL 2222.6°C25.9°C
JUL 2322.6°C25.8°C
JUL 2422.6°C25.6°C
JUL 2522.6°C25.4°C
JUL 2622.6°C25.2°C
JUL 2722.6°C25.1°C
JUL 2822.6°C24.9°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
January0°C2°C5°C
February1°C3°C6°C
March2°C6°C10°C
April4°C9°C14°C
May10°C15°C20°C
June15°C18°C22°C
July18°C23°C28°C
August19°C22°C25°C
September18°C21°C24°C
October12°C17°C22°C
November5°C10°C13°C
December0°C3°C7°C

Arrowrock Reservoir: Water Temperature by Location

Arrowrock Reservoir: Weather Forecast

July 22

° / °
overcast
rain: 13% | wind:

July 23

° / °
overcast
rain: 13% | wind:

July 24

° / °
light drizzle
rain: 6% | wind:

July 25

° / °
clear sky
rain: 1% | wind:

July 26

° / °
clear sky
rain: 3% | wind:

July 27

° / °
clear sky
rain: 1% | wind:

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.

Nearby Lakes

Frequently Asked Questions

What is the current water temperature in Arrowrock Reservoir?
Water Temperature in Arrowrock Reservoir today is 26.1°C.
What is the water temperature in Arrowrock Reservoir during the summer months?
The water temperature in Arrowrock Reservoir in summer fluctuates in the range of 15°C - 28°C.
Is it possible to swim in Arrowrock Reservoir and what are the possibilities for this?
Yes, swimming is possible in Arrowrock Reservoir, Idaho. However, local regulations, weather conditions, and water levels should be checked for safety and accessibility before planning a swim.