Learning to Read the Weather

When we are in the wilderness, we cannot afford to ignore the weather. Getting caught in a rainstorm unprepared can turn your weekend outing into an adventure in misery, or worse - hypothermia. Luckily, we don't need to be caught unprepared. With some knowledge and a few easy techniques, we can predict the weather with a reasonable degree of accuracy.

At Home

Check the forecast for the area where you will be hiking. There are weather resources listed in the links section that can provide a wealth of forecast information. Know how to read the maps and plan for several days. If the forecast shows an oncoming low pressure front or unusually cold temps, plan accordingly.

On the Trail

When you wake up, look at the sky. Take notice of the clouds and note the direction and speed of the wind. Are the clouds big and puffy or thin and thread-like? How windy is it? Has the weather changed since yesterday? (See our cloud guide.)

Clear Skies - A deep blue sky devoid of afternoon clouds indicate that a high pressure system is present. Stable weather can be expected for the next few days.
Silver Lining - High cirrus clouds in the morning that weren't there yesterday suggest that a front moved in overnight. Precipitation may be likely later in the day. Afternoon clouds that appear earlier and develop higher each day suggest that precipitation is on the way. If these clouds are dissipating earlier, just the opposite is true. Expect that drier weather is on the way.
High Winds - winds that have increased since the day before or that have changed direction may indicate a significant change in weather.
Cool Summer Breeze - a decidedly cool breeze in the mountains on a hot summer day may feel nice, but could also indicate that rain is falling on a nearby slope. Depending on wind direction and speed, this could indicate that more showers will develop or that a weather system is approaching.
Check pine cones - Pine cones open and close according to the relative humidity. Open pine cones indicate dry weather for the next couple days. Closed pine cones could indicate that precipitation is on the way

Other Signs to Watch for

Most animals are vulnerable to environmental changes that humans often can't detect. Swallows flying low may indicate the air pressure is dropping. Falling pressure may affect the digestive system of cows, making them less willing to go to pasture, causing them to lie down. Static electricity may increase the grooming activities of cats. The calls of some birds, including crows and geese, have been known to be more frequent with falling pressure. Deer and elk sometimes react to wind and air pressure by coming down from mountains and seeking shelter. Some species from rabbits to rattlesnakes to certain kinds of fish may feed more before a storm so they can seek shelter.

Some flowers close up as the humidity rises so rain doesn't wash away their pollen. The leaves of some trees curl just before a storm.
The higher the humidity, the better sound travels. Some English people gauged the chances of rain by the clarity with which they heard church bells sound.
A drop in barometric pressure often affects people with joint diseases, bad teeth, recently healed broken bones, or corns and bunions, bringing pain or pressure to those areas of the body
Cicadas can't vibrate their wings when the humidity is very high, so may be silent when rain is approaching. Flying insects are more active when the air pressure drops and stay closer to the ground, so they seem to be swarming before a rain storm.
The chirping of a cricket has been shown to provide a close indication of air temperature. By counting the number of cricket chirps in a 14-second period and adding 40, the total will equal the air temperature to within one degree 75% of the time.

Weather Clichés

Folk sayings about the weather are generally grounded in fact and can offer some level of accuracy when predicting the weather.

"Circle around the sun or moon, rain or snow soon" - If a whitish circle is noticeable around the moon (called a corona or blood on the moon), then a weather change is on the way. The halo around the sun or moon is a layer of cirrus clouds made of ice crystals. These ice crystals act as tiny prisms, forming a white or sometimes colorful halo around the sun or moon. This cirro-stratus cloud often indicates an approaching warm front and an associated area of low pressure. Rain or snow will not always follow, but there is a higher probability of it after a halo is seen, and the brighter the circle, the greater the probability.
"Cold is the night when the stars shine bright" - A clear sky without clouds means that the day's heat will quickly radiate away. Expect the temperature to drop and prepare accordingly.
"No weather's ill if the wind is still" - Still winds are a good sign that the weather will be fair and stable for the next few days. The exception are the quiet skies that often proceed afternoon thunderstorm systems in the summer.
"Red sky at morning, sailors take warning. Red sky at night, sailors delight" - As storms usually come from the west, a red sunrise in the morning , seen in the west, indicates humid air and the coming of stormy weather. A red sky in the evening, seen in the east, indicates the passing of stormy weather.
"When ropes twist, forget your haying" - A twisting rope or string indicates that humidity is rising, which may indicate the approach of a weather system. Don't use polyester string for this as it repels water and will not twist. A string made from cotton or some other natural fiber hung from a branch makes for a low cost weather forecast tool.
"When the stars begin to huddle, the land will soon be a puddle" - When clouds increase, whole areas of stars may be hidden by clouds with groups of stars, still in the clear sky, seem to huddle together. The clouds are increasing, so the chance of rain is increasing too.