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The weekend will be seasonable in terms of temperatures (mid-50s) with skies that will likely clear off by Sunday. All of this is a prelude to some very dramatic changes coming our way early next week. On Monday, expect clouds to increase and the winds to pick up ahead of a very strong cold front which will reach the region on Tuesday. The amount of rain and/or snow we get both here and in the mountains depends in large measure on what path the low pressure center will take. If it drops down more from the north (an inside slider pattern) then overall snow amounts will be smaller (at least in the mountains), but if it swings out and stays over water longer, it will likely pick up more moisture and the mountains will get hit pretty hard. Either way it will get very cold starting Wednesday through the holiday weekend.

Some people assume the temperature on one side of their house should be the same as the other (and they thus compare one thermometer’s temperature to another), but that’s not always true. Temperatures can vary greatly depending on a thermometer’s location.

Usually the problem has to do with where the sensors are placed. They have to be out of the sun, and away from any surface that might be getting hit by the sun. One side of your house can be significantly warmer than another, especially if there’s any contamination by the sun’s rays. If different thermometers start out the same and then diverge during the course of a day, that tells me they might be getting some sunlight contamination.

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What NOT to do…

If you really want to be official, you should follow what the National Weather Service does when they house their thermometers. According to the NWS, readings should be taken approximately five feet off the ground, and placed in such a way that they don’t come into contact with another building. They do this for a couple of reasons. Getting it off the ground will keep the readings from being too low on clear nights when radiational cooling can freeze the ground, while air temperatures at eye level can be ten or more degrees warmer. And on a cold night, heat coming off a building can easily contaminate temperature readings.

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The thermometer is usually enclosed in a well ventilated (slatted vents are preferable so no sunlight leaks in) white box, again keeping the sensor itself away from the box’s walls. The white color will reflect the sun’s radiation, giving you a truer reading of the air’s temperature. If you make it yourself, paint with a high-gloss enamel, which reflects more efficiently than a flat or satin finish. And try to keep the box relatively clean.

All of this can give you readings that any weather observer would be proud of.

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