December Weather at Jack Mc Namara Field United States

Daily high temperatures are around 54°F, rarely falling below 48°F or exceeding 60°F. The lowest daily average high temperature is 53°F on December 26.

Daily low temperatures are around 43°F, rarely falling below 35°F or exceeding 52°F. The lowest daily average low temperature is 42°F on December 22.

For reference, on August 21, the hottest day of the year, temperatures at Jack Mc Namara Field typically range from 53°F to 63°F, while on December 22, the coldest day of the year, they range from 42°F to 53°F.

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.

Ancud, Chile (6,586 miles away) and Cygnet, Australia (8,045 miles) are the far-away foreign places with temperatures most similar to Jack Mc Namara Field (view comparison).

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The month of December at Jack Mc Namara Field experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 68% throughout the month.

The clearest day of the month is December 9, with clear, mostly clear, or partly cloudy conditions 33% of the time.

For reference, on January 9, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 69%, while on August 2, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 88%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. At Jack Mc Namara Field, the chance of a wet day over the course of December is decreasing, starting the month at 51% and ending it at 45%.

For reference, the year's highest daily chance of a wet day is 52% on November 30, and its lowest chance is 1% on August 2.

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 at Jack Mc Namara Field is decreasing, starting the month at 9.7 inches, when it rarely exceeds 17.2 inches or falls below 3.3 inches, and ending the month at 9.0 inches, when it rarely exceeds 15.7 inches or falls below 2.8 inches.

The highest average 31-day accumulation is 10.0 inches on December 10.

Over the course of December at Jack Mc Namara Field, the length of the day is essentially constant. The shortest day of the month is December 21, with 9 hours, 8 minutes of daylight and the longest day is December 1, with 9 hours, 21 minutes of daylight.

The earliest sunrise of the month at Jack Mc Namara Field is 7:25 AM on December 1 and the latest sunrise is 19 minutes later at 7:44 AM on December 31.

The earliest sunset is 4:46 PM on December 8 and the latest sunset is 10 minutes later at 4:56 PM on December 31.

Daylight saving time is observed at Jack Mc Namara Field 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 5:42 AM and sets 15 hours, 13 minutes later, at 8:55 PM, while on December 21, the shortest day of the year, it rises at 7:41 AM and sets 9 hours, 8 minutes later, at 4:49 PM.

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.

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.

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 at Jack Mc Namara Field is essentially constant during December, remaining around 0% throughout.

For reference, on September 4, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.

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 at Jack Mc Namara Field is essentially constant during December, remaining within 0.2 miles per hour of 10.1 miles per hour throughout.

For reference, on December 14, the windiest day of the year, the daily average wind speed is 10.3 miles per hour, while on September 24, the calmest day of the year, the daily average wind speed is 7.3 miles per hour.

The highest daily average wind speed during December is 10.3 miles per hour on December 14.

The hourly average wind direction at Jack Mc Namara Field throughout December is predominantly from the south, with a peak proportion of 47% on December 31.

Jack Mc Namara Field is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average surface water temperature at Jack Mc Namara Field is essentially constant during December, remaining within 1°F of 52°F throughout.

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).

While it does not do so every year, freezing temperatures are seen at Jack Mc Namara Field over some winters. The day least likely to be in the growing season is January 16, with a 55% chance.

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 at Jack Mc Namara Field are gradually increasing during December, increasing by 45°F, from 1,363°F to 1,408°F, over the course of the month.

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 at Jack Mc Namara Field is essentially constant during December, remaining within 0.1 kWh of 1.5 kWh throughout.

The lowest average daily incident shortwave solar energy during December is 1.4 kWh on December 25.

For the purposes of this report, the geographical coordinates of Jack Mc Namara Field are 41.778 deg latitude, -124.236 deg longitude, and 52 ft elevation.

The topography within 2 miles of Jack Mc Namara Field contains only modest variations in elevation, with a maximum elevation change of 98 feet and an average elevation above sea level of 25 feet. Within 10 miles contains only modest variations in elevation (1,765 feet). Within 50 miles contains very significant variations in elevation (7,162 feet).

The area within 2 miles of Jack Mc Namara Field is covered by herbaceous vegetation (52%) and water (40%), within 10 miles by water (64%) and trees (21%), and within 50 miles by water (51%) and trees (36%).