More about sea weather
What is sea weather?
Marine weather forecasts predict winds, waves, and storms to assist maritime activities. Observations at sea collect data from buoys, ships, and satellites to monitor weather and ocean conditions in real time.
Frequently asked questions about sea weather
Where can I find the forecast for a specific stretch at sea?
The chart forecast is available under 'detailed' in the sea and coastal weather section: Marine and coastal weather (SMHI)
Where can I find the sea water level
The sea water level for a specific location can be found here: Sea levels and waves (SMHI)
Where can I see where there is algal bloom?
The current map for algal bloom can be found here: Algal Situation - Algal Map - Days (SMHI)
For lakes, we recommend contacting the relevant municipality.
Marine environmental monitoring
How are our oceans doing?
SMHI assesses the health of the ocean by conducting marine environmental monitoring. In various areas, SMHI measures conditions below the surface. The latest measurement results are shown in three areas: biodiversity, eutrophication, and habitats.
Frequently asked questions about marine environmental monitoring
The difference between the two systems is that the zero level for one (RW, water level relative to mean sea level) is 'anchored' to the water surface, whereas the zero level for the other (RH 2000, National Height System 2000) is 'anchored' to the bedrock.
For a single location and year, the difference is simply a matter of adding or subtracting a few centimetres to convert between the two. However, the mean level of water changes over time, and we must consider both local land uplift and global sea level rise when comparing water levels across different years or decades.
Both height systems have their advantages. Stating water levels relative to mean sea level allows us, for example, to compare extreme levels across years and observe how much these levels deviate from the mean. On the other hand, stating water levels in RH 2000 makes it easier to relate them to buildings and other land structures, where RH 2000 is the predominant height system. Additionally, depths in nautical charts become more stable when indicated in RH 2000.