Average Weather in Norcross Georgia, United States

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2. United States
3. Georgia
4. Gwinnett County
5. Norcross

In Norcross, the summers are hot and muggy, the winters are cold and wet, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 35°F to 89°F and is rarely below 22°F or above 95°F.

The hot season lasts for 3.8 months, from May 24 to September 17, with an average daily high temperature above 82°F. The hottest day of the year is July 23, with an average high of 89°F and low of 71°F.

The cool season lasts for 2.9 months, from November 28 to February 26, with an average daily high temperature below 60°F. The coldest day of the year is January 23, with an average low of 35°F and high of 52°F.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

In Norcross, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Norcross begins around July 19 and lasts for 4.2 months, ending around November 24. On October 8, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 67% of the time, and overcast or mostly cloudy 33% of the time.

The cloudier part of the year begins around November 24 and lasts for 7.8 months, ending around July 19. On January 3, the cloudiest day of the year, the sky is overcast or mostly cloudy 54% of the time, and clear, mostly clear, or partly cloudy 46% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Norcross varies throughout the year.

The wetter season lasts 3.8 months, from May 4 to August 30, with a greater than 32% chance of a given day being a wet day. The chance of a wet day peaks at 43% on July 9.

The drier season lasts 8.2 months, from August 30 to May 4. The smallest chance of a wet day is 20% on October 29.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 43% on July 9.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Norcross experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year in Norcross. The most rain falls during the 31 days centered around March 1, with an average total accumulation of 4.6 inches.

The least rain falls around October 24, with an average total accumulation of 3.0 inches.

Snowfall

The sliding 31-day liquid-equivalent quantity of snowfall in Norcross does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.

The length of the day in Norcross varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 54 minutes of daylight; the longest day is June 21, with 14 hours, 25 minutes of daylight.

The earliest sunrise is at 6:25 AM on June 12, and the latest sunrise is 1 hour, 34 minutes later at 7:59 AM on November 4. The earliest sunset is at 5:27 PM on December 4, and the latest sunset is 3 hours, 24 minutes later at 8:52 PM on June 29.

Daylight saving time (DST) is observed in Norcross during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Norcross experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 4.2 months, from May 23 to September 29, during which time the comfort level is muggy, oppressive, or miserable at least 21% of the time. The muggiest day of the year is July 25, with muggy conditions 84% of the time.

The least muggy day of the year is February 25, when muggy conditions are essentially unheard of.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Norcross experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.8 months, from October 19 to May 13, with average wind speeds of more than 2.9 miles per hour. The windiest day of the year is March 8, with an average hourly wind speed of 3.7 miles per hour.

The calmer time of year lasts for 5.2 months, from May 13 to October 19. The calmest day of the year is August 5, with an average hourly wind speed of 2.2 miles per hour.

The predominant average hourly wind direction in Norcross varies throughout the year.

The wind is most often from the east for 3.7 months, from August 11 to December 3, with a peak percentage of 47% on September 8. The wind is most often from the west for 8.3 months, from December 3 to August 11, with a peak percentage of 35% on January 1.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences significant seasonal variation over the course of the year.

The brighter period of the year lasts for 4.6 months, from April 12 to August 30, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest day of the year is June 6, with an average of 6.8 kWh.

The darker period of the year lasts for 2.8 months, from November 12 to February 6, with an average daily incident shortwave energy per square meter below 3.4 kWh. The darkest day of the year is December 24, with an average of 2.5 kWh.

For the purposes of this report, the geographical coordinates of Norcross are 33.941 deg latitude, -84.214 deg longitude, and 994 ft elevation.

The topography within 2 miles of Norcross contains only modest variations in elevation, with a maximum elevation change of 190 feet and an average elevation above sea level of 1,006 feet. Within 10 miles contains only modest variations in elevation (869 feet). Within 50 miles contains very significant variations in elevation (3,360 feet).

The area within 2 miles of Norcross is covered by artificial surfaces (100%), within 10 miles by artificial surfaces (88%), and within 50 miles by trees (57%) and artificial surfaces (26%).

This report illustrates the typical weather in Norcross, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Norcross.

For each station, the records are corrected for the elevation difference between that station and Norcross according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Norcross is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Norcross and a given station.

The stations contributing to this reconstruction are: Dekalb-Peachtree Airport (76%, 11 kilometers, southwest); Cherokee County Airport (9%, 44 kilometers, northwest); Barrow County Airport (8%, 51 kilometers, east); and Lee Gilmer Memorial Airport (7%, 51 kilometers, northeast).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.