Stony Brook at RT 20 at Waltham, Massachusetts water temperature
Stony Brook at RT 20 at Waltham, Massachusetts · River
The current water temperature at Stony Brook at RT 20 at Waltham is 18.8 °C (as of September 20, 2026, source: USGS).
A river can change temperature within hours — snowmelt, rain or power-plant operations show up immediately. That is why the measured value counts here, not an estimate.
Measurement series & statistics
This measurement series includes 453 data points since July 22, 2026.
Lowest recorded value: 18.8 °C on September 20, 2026 · highest value: 27.4 °C on August 8, 2026.
In September, temperatures have ranged between 18.8 °C and 24.2 °C.
The current value is 3.0 °C below the September average of this series.
Nearby waters
Frequently asked questions
Can you swim at Stony Brook at RT 20 at Waltham right now?
The current water temperature is 18.8 °C. See live swimming conditions, weather and quality in the BrrChecker app.
How warm is the water at Stony Brook at RT 20 at Waltham?
Currently 18.8 °C (updated continuously).
How warm is at Stony Brook at RT 20 at Waltham in September?
In September, the water temperature recently averaged 21.8 °C.
When is the water warmest at Stony Brook at RT 20 at Waltham?
Across the measurement record, August is on average the warmest month (24.1 °C).
