Clark Fork River Water Temperature Today
Clark Fork River, a river swimming spot in Montana, United States. The water peaks in the high teens to low twenties in July and August, and is near-freezing in midwinter.
In August Clark Fork River averages about 19°C, peaking near 19°C in July, August, September and dropping to roughly 2°C at its coldest.
River and swimming-hole temperatures are modelled from long-term monthly averages and refined with live air temperature, wind and UV. Moving water reacts faster to the weather than a lake or the sea.
Clark Fork River water temperature by month
| Month | Average water temperature | Swimming |
|---|---|---|
| January | 3.1°C | cold |
| February | 2.0°C | cold |
| March | 3.1°C | cold |
| April | 6.3°C | cold |
| May | 10.5°C | cool |
| June | 14.8°C | cool |
| July | 17.9°C | mild |
| August | 19.0°C | mild |
| September | 17.9°C | mild |
| October | 14.8°C | cool |
| November | 10.5°C | cool |
| December | 6.3°C | cold |
Clark Fork River swim conditions FAQ
What is the water temperature in Clark Fork River right now?
In August the water in Clark Fork River averages about 19°C. We refine that long-term average with today's air temperature, because this river responds quickly to the weather.
When is the best time to swim in Clark Fork River?
The comfortable swim season — 18°C or warmer — runs through August, with the warmest water in July, August, September at around 19°C.
Can you swim in Clark Fork River in winter?
Yes, but winter temperatures drop to roughly 2°C. Below 12°C, cold-water shock is the main risk: enter slowly, never swim alone, and limit time in the water.
Is Clark Fork River safe for swimming?
Moving and inland water carries different risks from the sea: check flow after rain, avoid weirs and undercut banks, look for submerged rocks before jumping, and respect local access rules and water-quality notices.
Water safety tips
- Check the flow rate after heavy rain — inland water can rise and speed up within hours.
- Never jump before checking depth and submerged rocks; levels change through the season.
- Enter slowly to control cold-water shock, and get out before you start shivering.
- Swim with someone else and agree an exit point downstream before you start.
- Winter water here can be near freezing; treat it as a cold-water swim.
Swim season here: August.
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