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By Laura McCloskey
What's the Weather in Noe Valley?
The weather in Noe Valley changes all the time. One minute it's sunny. Then it's foggy. Another minute it's windy. The next it's cold and rainy.
Sun in Noe Valley
The sun causes the weather in Noe Valley. When the sun is high in the sky, it heats the earth. After the sun sets, the earth cools down. The heating and cooling caused by the sun's rising and setting helps make all the different types of weather, like rain, wind, and fog.
Rain in Noe Valley
Water in the air creates the clouds above Noe Valley, the white and sometimes gray-looking forms we see in the sky. Rain falls from the clouds above Noe Valley when the water in the clouds collects and forms into heavy drops.
The most rain on record in Noe Valley fell during the winter of 186162, when it rained 49.27 inches. In recent years, the 199798 season was the wettest. That winter, it rained 47.19 inches.
January is usually the rainiest month in San Francisco, followed by February, December, and March. July is the driest month.
Fog in Noe Valley
Fog is a cloud that stays close to the ground. Fog forms in Noe Valley when warm, moist air from far out in the ocean moves over cooler water closer to the coast. The fog usually spreads over Noe Valley in the late evening and retreats back to the ocean in the morning, when the land grows warm.
Hills in Noe Valley
The hills encircling Noe Valley, and the ocean and bay surrounding the city, cause a pattern of weather in the neighborhood that is different from other places in San Francisco. For example, during the summer the fog covers many San Francisco neighborhoods all day long, while in Noe Valley the fog is often blocked by Twin Peaks. The twin hills create a barrier protecting the valley from wind and cooler air.
Snow in Noe Valley
It rarely ever snows in Noe Valley, but it did snow a few times. It snowed more than 7 inches on top of Twin Peaks on Feb. 5, 1887. That was over a hundred years ago! The most recent time it snowed was 30 years ago on Feb. 5, 1976. Then it snowed 1 inch in downtown San Francisco and almost 5 inches on top of Twin Peaks.
Clouds in Noe Valley
When you see clouds over Noe Valley, it might mean it's going to rain or it might not.
Noe Niño or Niña
Weather experts use the words "La Niña" and "El Niño," which mean "the girl" and "the boy" in Spanish, to describe weather patterns we experience in the United States. El Niño is a weather pattern created by the rapid warming of certain parts of the Pacific Ocean. It can cause large amounts of rain (or extremely dry weather) during the winter and spring. Because Noe Valley is located midway down the Pacific Coast, it's hard to tell whether an El Niño will bring us rain or clear skies.
La Niña is a weather pattern caused by the cooling of certain parts of the Pacific Ocean. It may cause hotter and dryer weather in the southwestern United States and colder and stormier weather to the north. Scientists say we are having La Niña this winter and that the weather in Noe Valley is likely to be normal to dry this spring.
A Tornado Near Noe Valley
Tornadoes do not usually happen in or near Noe Valley, but last year a tornado formed in South San Francisco, on March 21, 2005. The funnel-shaped windstorm, which rotated at rapid speeds of 70 to 110 miles per hour, flew over highway Interstate 280. The tornado caused a lot of damage to buildings, but no one was hurt.
Stratus clouds will cover the sky in a fluffy gray layer and will sometimes cause a coastal drizzle. When stratus clouds reach the ground, they are called fog.
Cirrus clouds are very high and wispy, and are not thick enough to cause rain themselves. Some people believe that if cirrus clouds make a halo around the sun, rain will come in a few days.
Cumulus clouds look like large balls of cotton, and they often cause rain. These clouds usually have round, lumpy tops and flatter bottoms.
How Do People Find Out About the Weather in Noe Valley?
Weather information is collected at a station run by the National Weather Service office located at the San Francisco Airport. The National Weather Service takes weather measurements, such as rainfall amounts, from 13 locations, two of which are very close to Noe Valley: Duboce Park and Mission Dolores.
For more information about the National Weather Service and for a weather forecast, go to www.wrh.noaa.gov/mtr/.
If you would like to find the current weather, visit the web site www.ozdachs.com/weather/.
If you would like to read some historical statistics on the weather in San Francisco, go to the site http://ggweather.com.
If you don't have a computer, listen to KCBS-740AM for weather updates.
Special thanks to meteorologist Jan Null, author of Climate of San Francisco and of the Golden Gate Weather Services web site; John Monteverdi, professor at San Francisco State University; and the articles "Climate Experts Predict La Niña Phenomenon" (Feb. 2, 2006) and "Strong South San Francisco Weather Determined to Be Tornado" (March 21, 2005), by the Associated Press on SFGate.com.