Delaware River Water Temperature Today
Delaware River, a river swimming spot in Pennsylvania, United States. The water warms into the mid-20s °C and holds it through the swim season, and is near-freezing in midwinter.
In August Delaware River averages about 26°C, peaking near 26°C in July, August, September and dropping to roughly 3°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.
Delaware River water temperature by month
| Month | Average water temperature | Swimming |
|---|---|---|
| January | 4.5°C | cold |
| February | 3.0°C | cold |
| March | 4.5°C | cold |
| April | 8.8°C | cold |
| May | 14.5°C | cool |
| June | 20.3°C | warm |
| July | 24.5°C | hot |
| August | 26.0°C | hot |
| September | 24.5°C | hot |
| October | 20.3°C | warm |
| November | 14.5°C | cool |
| December | 8.8°C | cold |
Delaware River swim conditions FAQ
What is the water temperature in Delaware River right now?
In August the water in Delaware River averages about 26°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 Delaware River?
The comfortable swim season — 18°C or warmer — runs through June, July, August, September, October, with the warmest water in July, August, September at around 26°C.
Can you swim in Delaware River in winter?
Yes, but winter temperatures drop to roughly 3°C. Below 12°C, cold-water shock is the main risk: enter slowly, never swim alone, and limit time in the water.
Is Delaware 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: June, July, August, September, October.
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