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Grayrocks Reservoir — Current Water Temperature, Annual Trends and Forecast

This page provides information on the current water temperature in Grayrocks Reservoir, trends, monthly ranges and the forecast for the coming days.

Horsetooth Reservoir, United States
Horsetooth Reservoir, United States © By Ken Gallager, Public domain

Current Water Temperature

20.4°C
Today
20.5°C
Yesterday
20.5°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 Grayrocks Reservoir today is 20.4°C.

Water Temperature: Daily Trends, Historical Records, and Forecast

✅ As of today, the minimum water temperature ranges from 68°F (20°C) to 74°F (23°C). The water is warm and pleasant for swimming, and in this range, one can stay in the water for extended periods without the risk of hypothermia. This is the ideal temperature for relaxation, swimming, and water sports. Families with children, as well as outdoor enthusiasts, will enjoy swimming and time spent in the water. For most people, this is the optimal temperature for a comfortable beach experience. 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 May 10 to June 10

Table of Daily Sea Temperature Data

Date Current Average Forecast
JUN 219.5°C18.0°C
JUN 319.4°C18.0°C
JUN 419.6°C18.0°C
JUN 519.8°C18.0°C
JUN 620.3°C18.0°C
JUN 720.5°C18.0°C
JUN 820.9°C18.0°C
JUN 1018.0°C20.3°C
JUN 1118.0°C20.2°C
JUN 1218.0°C20.0°C
JUN 1318.0°C19.9°C
JUN 1418.0°C19.8°C
JUN 1518.0°C19.7°C
JUN 1618.0°C19.6°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°C3°C7°C
February0°C3°C7°C
March0°C6°C12°C
April4°C9°C15°C
May8°C14°C21°C
June15°C18°C21°C
July21°C23°C26°C
August21°C23°C26°C
September17°C21°C24°C
October9°C14°C19°C
November6°C10°C14°C
December3°C5°C7°C

Grayrocks Reservoir: Water Temperature by Location

Grayrocks Reservoir: Weather Forecast

June 9

° / °
overcast
rain: 30% | wind:

June 10

° / °
overcast
rain: 7% | wind:

June 11

° / °
overcast
rain: 7% | wind:

June 12

° / °
overcast
rain: 3% | wind:

June 13

° / °
overcast
rain: 9% | wind:

Location & Local Information

Grayrocks Reservoir typically runs cold for much of the year owing to its high‑plain location and snowmelt-fed inflows. In spring (April–May) surface temperatures commonly range from roughly 35–55°F (2–13°C) as snowmelt and cool weather keep the water chillier. Summer months (June–August) bring the warmest conditions, with surface readings frequently between about 60–75°F (15–24°C) and occasionally topping the high 70s °F (around 24–26°C) in warm, calm spells. By early fall (September–October) temperatures usually drop back into the 50s–60s °F (10–18°C), and in winter the reservoir often sits at or near freezing, with ice forming on the surface when conditions are sustained below 32°F (0°C).

Swimming at Grayrocks Reservoir is generally allowed as part of its recreational use, but it is not structured like a staffed beach and conditions can make swimming risky. Cold water, sudden temperature stratification, steep drop‑offs, fluctuating water levels for irrigation, boat traffic, and the absence of lifeguards mean swimmers should exercise caution, use flotation, and be mindful of posted rules or temporary advisories. Many visitors choose to swim during the warmest weeks of summer, but even then water can feel cool compared with low‑elevation lakes.

Nearby Lakes

Frequently Asked Questions

What is the current water temperature in Grayrocks Reservoir?
Water Temperature in Grayrocks Reservoir today is 20.4°C.
What is the water temperature in Grayrocks Reservoir during the summer months?
The water temperature in Grayrocks Reservoir in summer fluctuates in the range of 15°C - 26°C.
Is it possible to swim in Grayrocks Reservoir and what are the possibilities for this?
Yes, it is possible to swim in Grayrocks Reservoir, Wyoming. However, as with any natural body of water, conditions can vary, so it's recommended to check local regulations and safety guidelines.