Poseidon is the name for Greece-based weather system operated by the Hellenic Center for Marine Research and their Institute of Oceanography.
The weather information for Greece is produced by a series of hundreds of weather buoys throughout Greek waters.
While it's mainly intended for those traveling by water, it also provides a huge amount of useful information for other travel as well, including where it is raining or will be raining, where the dust clouds from Africa are flowing, and what the winds can be expected to do.
Greeks pay careful attention to the predictions, and they are considered to be highly accurate by ferry captains and fishermen.
The Poseidon Weather System also functions on Android phones. The 4.0 version was just released in February 2015. It can be downloaded as a free app at the Google Store. As of summer 2017, this is the only version of the system available for your phone.
How to Use the Poseidon Website
Most travelers will want to select the Weather Forecast from the lower part of the left-hand navigation bar. This will open up a page with a multi-colored weather map of Greece.
At the left side, there is a small white box with rows of numbers in it, showing the date and the time in UTC. The date is given European-fashion, with the day first and the month second, which can cause some confusion in lower-numbered months. This box allows you to select a forecast in six-hour increments.
For most people, the weather in the middle of the night is not as important as the weather during the day. The time is given in UTC, or Coordinated Universal Time, the "master clock" used in shipping and aviation. This is the same as International Atomic Time, and it is based on a 24-hour clock, so 6pm would be 18:00.
In Greece, the "real time" during Daylight Savings Time is UTC +2, so 18:00 would refer to 8pm.
Once you have decided the time period you want the Greek weather forecast for, select the "Parameter" from the box above. You have your choice of seeing a map reflecting surface wind conditions, rainfall, snowfall, wave height, rainfall, cloudiness, air temperature, dust load, fog, and atmospheric pressure.
Once you've selected the desired time and wind condition or another category, press the "Display" box and the colored image will change to reflect your choices.
If you're traveling by sea, you can also select the "Waves Forecast" for Greece model from the left-hand navigation bar on the main page. This will give you wave predictions broken down into three-hour increments.
Poseidon Weather is also available as a free Android app.
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