Porsgrunn — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Porsgrunn, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Porsgrunn today is 13.6°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 54°F (12°C) to 60°F (15°C). The water is significantly warmer, and swimming becomes possible for most people. However, caution may still be required for prolonged stays in the water, as extended exposure can cause discomfort. This is a suitable temperature range for short swims and for those accustomed to cooler water. For more comfortable swimming, it is recommended to use proper gear. 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
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| SEP 13 | 14.4°C | 17.0°C | |
| SEP 14 | 13.8°C | 17.0°C | |
| SEP 15 | 14.2°C | 17.0°C | |
| SEP 16 | 14.2°C | 17.0°C | |
| SEP 17 | 13.6°C | 17.0°C | |
| SEP 18 | 14.2°C | 17.0°C | |
| SEP 19 | 13.8°C | 17.0°C | |
| SEP 20 | 13.7°C | 17.0°C | |
| SEP 21 | 17.0°C | 13.8°C | |
| SEP 22 | 17.0°C | 13.9°C | |
| SEP 23 | 17.0°C | 14.1°C | |
| SEP 24 | 17.0°C | 14.3°C | |
| SEP 25 | 17.0°C | 14.5°C | |
| SEP 26 | 17.0°C | 14.6°C | |
| SEP 27 | 17.0°C | 14.8°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 |
|---|---|---|---|
| January | 0°C | 3°C | 6°C |
| February | 0°C | 3°C | 6°C |
| March | 0°C | 4°C | 7°C |
| April | 3°C | 7°C | 11°C |
| May | 7°C | 12°C | 17°C |
| June | 11°C | 17°C | 23°C |
| July | 16°C | 21°C | 26°C |
| August | 16°C | 21°C | 26°C |
| September | 12°C | 17°C | 22°C |
| October | 7°C | 11°C | 14°C |
| November | 3°C | 7°C | 10°C |
| December | 0°C | 4°C | 7°C |
Porsgrunn: Weather Forecast
September 21
September 22
September 23
September 24
September 25
September 26
Location & Local Information
Porsgrunn in Telemark County sits along the Skien–Porsgrunn watercourse and close to inland lakes such as Norsjø, and the freshwater bodies there show clear seasonal temperature swings. In summer, lake surface temperatures typically range from roughly 18–22 °C (64–72 °F), with shallow bays occasionally rising to 24 °C (75 °F) in warm spells; rivers like Skienselva are usually somewhat cooler, often 12–18 °C (54–64 °F) depending on flow and shading. During spring (April–May) lakes and rivers are cold, commonly 4–10 °C (39–50 °F) as snowmelt and runoff dominate, while autumn sees gradual cooling to about 10–16 °C (50–61 °F). In winter most small lakes approach 0–4 °C (32–39 °F) and can freeze, though fast-flowing river stretches may remain just above freezing.
Swimming in Porsgrunn’s freshwater is generally allowed and practiced at designated bathing spots and informal riverbanks, subject to local signage and water quality checks. Authorities monitor bacteria levels at popular sites during the bathing season, but swimmers should be aware of currents, boat traffic, sudden depth changes and colder temperatures outside summer months; lifeguard coverage is limited, so personal caution and checking local guidance are advisable before entering the water.