YOUR SMALL BOAT IS AN ISLAND IN A VAST SEA. The horizon stretches to infinity all around you. Your future — whether you will cruise in relative comfort or be tossed on the waves like a cork — depends solely on the weather. Sun, rain, wind… a typhoon… how will you know what to expect? The weather on the ocean can change from day to day, and it can still show you just how small you really are on this planet. Whether you are out on the ocean, a lake, a pond, or a river, knowing what the weather will do is one of the more important things you need to know about your environment. A sudden change in the weather, like a storm blowing in when you are on land, can make things inconvenient but rarely will it make things dangerous. But on the water, heavy winds or rain can turn a day on the water into a life or death situation.


Fortunately, mankind has known for centuries how to predict what the weather will do based on what we see in nature, from the birds and animals and clouds. As time progressed, early scientists who studied the weather found that as the weather changed so did the pressure and humidity. In the 1600s they devised tools like barometers, thermometers, anemometers, and hygrometers that could measure these values, and they have been used to the current day. With the advent of the Internet and the information age we can get the same information on our phones that the television weatherman does. Fortunately, each of these three eras have lessons to teach us about how to interpret the weather.

If the only clouds are high in the sky, it is a strong indicator that good weather is here to stay for a while.

If the only clouds are high in the sky, it is a strong indicator that good weather is here to stay for a while.

A ring around the moon is a good indicator of rain or snow.

A ring around the moon is a good indicator of rain or snow.

Red sky in morning, sailors take warning; red sky at night, sailors delight!

Red sky in morning, sailors take warning; red
sky at night, sailors delight!


Observation of the skies and sea birds and animals gave ancient mariners and shore-based fishermen insights into what the weather would do. These same observations can be used by today’s mariners and fishermen to forecast the weather. For example:

  • If the birds are flying high in the sky, fair weather will stay around.
  • Birds tend to take refuge as a storm approaches, so if you notice them roosting when they were flying before, a storm may be coming.
  • A ring around the moon at night, caused by moisture in the air, means that you will have rain or snow sometime in the next few days.
  • The higher the clouds are in the sky the fairer the weather will be.
  • Long, streamer-like clouds (cirrus clouds) indicate bad weather during the next 36 hours.
  • Altocumulus clouds, the ones that look like fish scales, indicate bad weather will be there within a day or two.
  • Tall, tower-like clouds (cumulus clouds) indicate showers later in the day.
  • Rain clouds (nimbostratus) that are hanging low and dark in the sky mean that rain will happen soon.
  • Rows of small, puffy clouds (cirrocumulus clouds) in a row indicate that cold weather is coming.
  • Winds which blow from the east can indicate an approaching storm front; Winds blowing in the opposite direction usually mean good weather.
  • Winds coming from the opposite of their normal direction often warn us about severe weather approaching.
  • If the sky is red at night, the next day will likely be clear; if red in the morning, expect rain by the end of the day; remember, “Red sky at night, sailor’s delight; red sky in morning, sailor take warning.”


Early Scientists

During the Age of Reason, which started in the early to mid-1600s and extended into the late 1700s, observation of the natural world and all of its aspects grew, as did the value placed on science and the respect given to scientists. It was during this period that the major weather related observations and instruments were first made. The mid-1600s saw the creation of the modern thermometer, barometer, hygrometer, and anemometer which were used to measure temperature, air pressure, humidity, and wind speed and direction. These five components were the basis for all weather research and allowed the scientists of the day to capture the data that would give them a better understanding of the world around them. It was from these studies that we found how high and low pressure fronts affected weather and how winds flowed as currents across the surface of the globe. The knowledge we gained here you can use yourself include:

  • Strong winds indicate high pressure differences, which can be a sign of advancing storm fronts.
  • Low air pressure, which is due to the temperature getting warmer, brings rain.
  • High air pressure, which is from colder temperatures making the air denser, brings clear skies and good weather.
  • Major weather systems often move from west to east.
  • Prevailing weather systems move from west to east, but individual weather patterns in your area may not, due to regional phenomena.


The best way to get current weather reports and forecasts while on the water is with a VHF ship-to-shore radio which can pick up U.S. Coast Guard and NOAA weather reports. These radios come in either handheld versions or versions that are installed on your boat or vessel. These provide the most current information and also provide information about areas on the water rather than areas on land.

  •  A gray dawn with foggy valleys indicates — surprise! — a clear day ahead.
  • A hazy ring around the sun or moon in summer is a reliable sign that the weather pattern is in for a change, usually bringing rain.
  • A heavy morning or late-evening dew (or frost in cold months) may indicate 12 hours of continued good weather.
  • Winds from the south tend to bring rain (old adage: “Wind from the south brings rain in its mouth”), while winds from the north are associated with clear weather. On a similar note, if the wind has been blowing for the past few hours, rushing clouds along, and then suddenly dies, you are in for a major storm.


To get ready to do your own weather forecasting while on the water, pull out that ancient high school science textbook and brush up on air pressure, humidity, and temperature. Next, work on being more observant about what is going on around you in the outdoors and the animals that live there. Then download the weather apps for your smartphone. Finally, get yourself a handheld or vessel mounted VHF radio so you can get the Coast Guard or NOAA weather channel. With time and attention you too will be able to know what the weather is going to do without having to watch the evening news the night before.



Cirrus: Quickly moving fairweather clouds can lead to a change in the weather on the following day.


Altocumulus: Result of warm, humid air. Thunderstorms are likely.


Altostratus: Gray or bluish clouds, blocking the sun. Mostly dry but can cause moisture buildup.


Stratocumulus: Rarely rainclouds, these usually point to dry weather.


Stratus: Fog-like cloud produces a fine mist, sometimes a drizzle.


Cumulus: Dry weather clouds can produce thunderstorms at high altitude.


Cumulonimbus: With these clouds, there is an extreme weather alert. Rains and thunderstorms.


Nimbostratus: Low-layer dark clouds almost always bring with them rain.


Cirrocumulus: Light heaps of clouds indicate a cold front approaching and perhaps light rain.


Cirrostratus: A pale veil of clouds blanket across the sky with rain within a day or so.


Editor’s Note: A version of this article first appeared in the August 2015 print issue of American Survival Guide.