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December Weather in Allen United States

Daily high temperatures decrease by 6°F, from 61°F to 55°F, rarely falling below 38°F or exceeding 73°F.

Daily low temperatures decrease by 6°F, from 42°F to 36°F, rarely falling below 24°F or exceeding 56°F.

For reference, on July 31, the hottest day of the year, temperatures in Allen typically range from 75°F to 95°F, while on January 5, the coldest day of the year, they range from 36°F to 55°F.

Average High and Low Temperature in December in Allen

Average High and Low Temperature in December in AllenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313120°F20°F25°F25°F30°F30°F35°F35°F40°F40°F45°F45°F50°F50°F55°F55°F60°F60°F65°F65°F70°F70°F75°F75°F80°F80°F85°F85°FNovJanDec 161°FDec 161°F42°F42°FDec 3155°FDec 3155°F36°F36°FDec 1157°FDec 1157°F39°F39°FDec 2156°FDec 2156°F37°F37°F
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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

Average Hourly Temperature in December in Allen

Average Hourly Temperature in December in AllenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNovJanvery coldvery coldcoldcoolcoolcomfortable
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Ar Rudayyif, Tunisia (5,702 miles away) and Açıkdere, Turkey (6,772 miles) are the far-away foreign places with temperatures most similar to Allen (view comparison).

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The month of December in Allen experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 40% to 44%. The highest chance of overcast or mostly cloudy conditions is 45% on December 26.

The clearest day of the month is December 3, with clear, mostly clear, or partly cloudy conditions 60% of the time.

For reference, on February 24, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 46%, while on October 4, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 74%.

Cloud Cover Categories in December in Allen

Cloud Cover Categories in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%NovJanOct 474%Oct 474%Dec 160%Dec 160%Dec 3156%Dec 3156%Dec 1158%Dec 1158%Dec 2156%Dec 2156%clearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Allen, the chance of a wet day over the course of December is decreasing, starting the month at 22% and ending it at 16%.

For reference, the year's highest daily chance of a wet day is 38% on May 31, and its lowest chance is 16% on December 31.

Over the course of December in Allen, the chance of a day with only rain decreases from 20% to 13%, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow remains an essentially constant 0% throughout.

Probability of Precipitation in December in Allen

Probability of Precipitation in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%0%2%2%4%4%6%6%8%8%10%10%12%12%14%14%16%16%18%18%20%20%22%22%24%24%NovJanDec 3116%Dec 3116%Dec 122%Dec 122%Dec 1119%Dec 1119%Dec 2119%Dec 2119%mixedrainsnow
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during December in Allen is decreasing, starting the month at 2.7 inches, when it rarely exceeds 5.0 inches or falls below 0.5 inches, and ending the month at 2.1 inches, when it rarely exceeds 4.6 inches or falls below 0.2 inches.

Average Monthly Rainfall in December in Allen

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Over the course of December in Allen, the length of the day is essentially constant. The shortest day of the month is December 21, with 9 hours, 58 minutes of daylight and the longest day is December 1, with 10 hours, 7 minutes of daylight.

Hours of Daylight and Twilight in December in Allen

Hours of Daylight and Twilight in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrNovJanDec 219 hr, 58 minDec 219 hr, 58 minnightnightdaydayDec 110 hr, 7 minDec 110 hr, 7 min
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in Allen is 7:12 AM on December 1 and the latest sunrise is 17 minutes later at 7:29 AM on December 31.

The earliest sunset is 5:19 PM on December 3 and the latest sunset is 11 minutes later at 5:30 PM on December 31.

Daylight saving time is observed in Allen during 2024, but it neither starts nor ends during December, so the entire month is in daylight saving time.

For reference, on June 20, the longest day of the year, the Sun rises at 6:18 AM and sets 14 hours, 21 minutes later, at 8:38 PM, while on December 21, the shortest day of the year, it rises at 7:26 AM and sets 9 hours, 58 minutes later, at 5:24 PM.

Sunrise & Sunset with Twilight and Daylight Saving Time in December in Allen

Sunrise & Sunset with Twilight and Daylight Saving Time in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031312 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMNovJan7:12 AM7:12 AMDec 15:19 PMDec 15:19 PM7:29 AM7:29 AMDec 315:30 PMDec 315:30 PM7:20 AM7:20 AMDec 115:20 PMDec 115:20 PM7:26 AM7:26 AMDec 215:24 PMDec 215:24 PMSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of December. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth in December in Allen

Solar Elevation and Azimuth in December in AllenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNovJan0010102020303000101020203030
northeastsouthwest
Solar elevation and azimuth over the course of December 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for December 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

Moon Rise, Set & Phases in December in Allen

Moon Rise, Set & Phases in December in AllenDec112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMNovJanNov 17:48 AMNov 17:48 AMNov 153:29 PMNov 153:29 PMDec 112:22 AMDec 112:22 AMDec 153:02 AMDec 153:02 AMDec 304:28 PMDec 304:28 PMJan 134:28 PMJan 134:28 PMJan 296:37 AMJan 296:37 AM7:53 AM7:53 AM6:32 PM6:32 PM5:07 PM5:07 PM7:59 AM7:59 AM7:46 AM7:46 AM5:29 PM5:29 PM4:34 PM4:34 PM7:55 AM7:55 AM7:33 AM7:33 AM5:11 PM5:11 PM5:28 PM5:28 PM8:20 AM8:20 AM7:45 AM7:45 AM6:17 PM6:17 PM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.
Dec 2024IlluminationMoonriseMoonsetMoonriseMeridian PassingDistance
1
0%7:46 AMESE5:29 PMSW-12:37 PMS245,247 mi
2
2%8:45 AMSE6:22 PMSW-1:34 PMS243,160 mi
3
7%9:41 AMSE7:22 PMWSW-2:31 PMS241,025 mi
4
13%10:30 AMESE8:27 PMWSW-3:28 PMS238,878 mi
5
22%11:12 AMESE9:34 PMWSW-4:23 PMS236,738 mi
6
32%11:48 AMESE10:41 PMWSW-5:14 PMS234,624 mi
7
43%12:20 PMESE11:47 PMW-6:03 PMS232,573 mi
8
50%12:50 PME--6:50 PMS230,661 mi
9
66%-12:53 AMW1:19 PME7:37 PMS229,003 mi
10
77%-2:00 AMW1:49 PME8:25 PMS227,755 mi
11
86%-3:08 AMWNW2:21 PMENE9:17 PMS227,091 mi
12
94%-4:20 AMWNW2:58 PMENE10:12 PMS227,171 mi
13
98%-5:33 AMWNW3:42 PMENE11:11 PMS228,102 mi
14
99%-6:46 AMWNW4:34 PMENE--
15
100%-7:55 AMNW5:34 PMNE12:13 AMS229,900 mi
16
99%-8:56 AMNW6:40 PMENE1:16 AMS232,465 mi
17
95%-9:46 AMWNW7:47 PMENE2:16 AMS235,594 mi
18
89%-10:27 AMWNW8:53 PMENE3:11 AMS239,013 mi
19
82%-11:01 AMWNW9:55 PMENE4:00 AMS242,422 mi
20
73%-11:29 AMWNW10:53 PME4:45 AMS245,541 mi
21
64%-11:55 AMW11:49 PME5:26 AMS248,132 mi
22
50%-12:19 PMW-6:06 AMS250,019 mi
23
44%12:44 AME12:42 PMW-6:44 AMS251,091 mi
24
35%1:39 AME1:07 PMWSW-7:23 AMS251,311 mi
25
26%2:35 AMESE1:33 PMWSW-8:04 AMS250,707 mi
26
18%3:32 AMESE2:04 PMWSW-8:48 AMS249,371 mi
27
11%4:32 AMESE2:39 PMWSW-9:36 AMS247,445 mi
28
5%5:34 AMESE3:22 PMWSW-10:28 AMS245,109 mi
29
2%6:35 AMSE4:13 PMSW-11:24 AMS242,565 mi
30
0%7:33 AMSE5:11 PMSW-12:22 PMS240,010 mi
31
1%8:25 AMESE6:16 PMWSW-1:21 PMS237,618 mi

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.

The chance that a given day will be muggy in Allen is essentially constant during December, remaining around 1% throughout.

For reference, on July 5, the muggiest day of the year, there are muggy conditions 86% of the time, while on January 21, the least muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in December in Allen

Humidity Comfort Levels in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%NovJanDec 12%Dec 12%Dec 311%Dec 311%Dec 111%Dec 111%Dec 211%Dec 211%humidhumiddrydrycomfortablecomfortablemuggymuggy
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 Allen is essentially constant during December, remaining within 0.1 miles per hour of 10.4 miles per hour throughout.

For reference, on April 1, the windiest day of the year, the daily average wind speed is 11.9 miles per hour, while on August 22, the calmest day of the year, the daily average wind speed is 8.0 miles per hour.

Average Wind Speed in December in Allen

Average Wind Speed in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mph14 mph14 mph16 mph16 mphNovJanDec 110.5 mphDec 110.5 mphDec 3110.3 mphDec 3110.3 mphDec 1610.3 mphDec 1610.3 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The wind direction in Allen during December is predominantly out of the south from December 1 to December 22 and the north from December 22 to December 31.

Wind Direction in December in Allen

Wind Direction in December in AllenSNDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%20%80%40%60%60%40%80%20%100%0%NovJansouthnortheastwest
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Allen typically lasts for 8.4 months (256 days), from around March 9 to around November 20, rarely starting before February 14 or after April 2, and rarely ending before October 31 or after December 11.

The month of December in Allen is more likely than not fully outside of the growing season, with the chance that a given day is in the growing season rapidly decreasing from 26% to 0% over the course of the month.

Time Spent in Various Temperature Bands and the Growing Season in December in Allen

Time Spent in Various Temperature Bands and the Growing Season in December in Allengrowing seasonDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%NovJanDec 126%Dec 126%Dec 310%Dec 310%Dec 1110%Dec 1110%Dec 213%Dec 213%50%Nov 2050%Nov 20freezingvery coldcoldcoolcomfortablewarm
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in Allen are gradually increasing during December, increasing by 101°F, from 5,922°F to 6,023°F, over the course of the month.

Growing Degree Days in December in Allen

Growing Degree Days in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031315,700°F5,700°F5,800°F5,800°F5,900°F5,900°F6,000°F6,000°F6,100°F6,100°F6,200°F6,200°F6,300°F6,300°F6,400°F6,400°F6,500°F6,500°FNovJanDec 15,922°FDec 15,922°FDec 316,023°FDec 316,023°FDec 115,965°FDec 115,965°FDec 215,998°FDec 215,998°F
The average growing degree days accumulated over the course of December, with 25th to 75th and 10th to 90th percentile bands.

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 in Allen is essentially constant during December, remaining within 0.1 kWh of 2.9 kWh throughout.

The lowest average daily incident shortwave solar energy during December is 2.8 kWh on December 21.

Average Daily Incident Shortwave Solar Energy in December in Allen

Average Daily Incident Shortwave Solar Energy in December in AllenDec11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310.0 kWh0.0 kWh0.5 kWh0.5 kWh1.0 kWh1.0 kWh1.5 kWh1.5 kWh2.0 kWh2.0 kWh2.5 kWh2.5 kWh3.0 kWh3.0 kWh3.5 kWh3.5 kWh4.0 kWh4.0 kWh4.5 kWh4.5 kWh5.0 kWh5.0 kWhNovJanDec 212.8 kWhDec 212.8 kWhDec 13.0 kWhDec 13.0 kWhDec 312.8 kWhDec 312.8 kWhDec 112.9 kWhDec 112.9 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

For the purposes of this report, the geographical coordinates of Allen are 33.103 deg latitude, -96.671 deg longitude, and 656 ft elevation.

The topography within 2 miles of Allen contains only modest variations in elevation, with a maximum elevation change of 131 feet and an average elevation above sea level of 648 feet. Within 10 miles also contains only modest variations in elevation (331 feet). Within 50 miles contains only modest variations in elevation (735 feet).

The area within 2 miles of Allen is covered by artificial surfaces (77%) and cropland (23%), within 10 miles by artificial surfaces (54%) and cropland (24%), and within 50 miles by grassland (37%) and cropland (33%).

This report illustrates the typical weather in Allen, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Allen.

For each station, the records are corrected for the elevation difference between that station and Allen 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 Allen is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Allen and a given station.

The stations contributing to this reconstruction are:

  • McKinney Municipal Airport (KTKI, 58%, 8 mi, northeast, -72 ft elevation change)
  • Addison Airport (KADS, 26%, 13 mi, southwest, -13 ft elevation change)
  • Rockwall Municipal (KF46, 16%, 18 mi, southeast, -82 ft elevation change)

Sources mapKTKI, 58%8 mi, -72 ftKADS, 26%13 mi, -13 ftKF46, 16%18 mi, -82 ft© OpenStreetMap contributors

To get a sense of how much these sources agree with each other, you can view a comparison of Allen and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports and weather stations are provided by AskGeo.com .

Maps are © OpenStreetMap contributors.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.

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