Source: SMHI S-HYPE · descriptive facts, not a forecast
Calculated water temperature at Långforsen on September 25: about 10,3 °C. The last published measurement is 4 days old — the figure firms up as SMHI publishes new measurements.
The temperature at the surface probably swings between +0,6 °C and +1,9 °C compared with the deeper water today — coldest just before first light, warmest just after the afternoon's highest sun. How large the swing is depends on how much sun the water gets, the water's size and depth, cold rain, and wind mixing the surface.
The temperature at the surface swings from about 10,6 °C to about 11,3 °C — warmest around 04:00.
A modelled estimate based on the day's weather, the lake's depth and the wind across the day. The dashed line from 02:00 is a look ahead from the latest measurements.
What does the water temperature mean for the fishing?
The water at Långforsen is currently around 10,3°. How the temperature plays in is something Huggtabell.se weighs together with weather, air pressure and moon into a huggtabell for Långforsen. Today's table is free, and if you want to plan further ahead they have forecasts reaching seven days out.