Naperville 14 Day Long Range Forecast

The day label given represents the local day relative to the local time for the location you are looking at.
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This time is corrected for local time zones and where possible for daylight saving times.
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The wind direction we use on this page is the direction the wind is coming from, given in a 16 point compass format.
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This refers to the sustained average wind speed, normally averaged over a period of 10 minutes for up to 3 hrs.
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Temperature from our forecast perspective are fairly well defined, they are what we would expect to measure in a standard meteorological screen (in other words, shaded and well ventilated) at 2 metres above ground level.
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The relative humidity is the percent of saturation humidity, generally calculated in relation to saturated vapour density.
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The value given is a total predicted for the previous 3 hrs and includes the time of the forecast being looked at.
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The total amount of cloud as a percentage is derived from looking at cloud cover throughout the atmosphere and estimating how these combine when looked at from the ground.
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Here we try to capture the feel of the weather as an image – it will never be perfect but is useful for a quick overview.
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When we measure for forecast air pressure we are normally doing this relative to a certain height and most commonly relative to Mean Sea Level.
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