December Weather in Grand Rapids Michigan, United States

Daily high temperatures decrease by 8°F, from 40°F to 32°F, rarely falling below 19°F or exceeding 54°F.

Daily low temperatures decrease by 8°F, from 29°F to 21°F, rarely falling below 7°F or exceeding 40°F.

For reference, on July 18, the hottest day of the year, temperatures in Grand Rapids typically range from 63°F to 83°F, while on January 29, the coldest day of the year, they range from 18°F to 30°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.

Dnipro, Ukraine (5,173 miles away) and Aleksandrovskoye, Russia (5,610 miles) are the far-away foreign places with temperatures most similar to Grand Rapids (view comparison).

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The month of December in Grand Rapids experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 63% to 69%.

The clearest day of the month is December 1, with clear, mostly clear, or partly cloudy conditions 37% of the time.

For reference, on January 7, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 69%, while on August 6, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 67%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Grand Rapids, the chance of a wet day over the course of December is essentially constant, remaining around 24% throughout.

For reference, the year's highest daily chance of a wet day is 33% on May 23, and its lowest chance is 17% on February 8.

Over the course of December in Grand Rapids, the chance of a day with only rain decreases from 16% to 10%, the chance of a day with mixed snow and rain remains an essentially constant 4% throughout, and the chance of a day with only snow increases from 6% to 11%.

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 Grand Rapids is decreasing, starting the month at 1.7 inches, when it rarely exceeds 3.0 inches or falls below 0.6 inches, and ending the month at 1.0 inches, when it rarely exceeds 2.1 inches or falls below 0.1 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day snowfall during December in Grand Rapids is increasing, starting the month at 4.1 inches, when it rarely exceeds 10.1 inches or falls below 0.2 inches, and ending the month at 6.8 inches, when it rarely exceeds 12.7 inches or falls below 1.6 inches.

Over the course of December in Grand Rapids, the length of the day is essentially constant. The shortest day of the month is December 20, with 9 hours, 0 minutes of daylight and the longest day is December 1, with 9 hours, 14 minutes of daylight.

The earliest sunrise of the month in Grand Rapids is 7:54 AM on December 1 and the latest sunrise is 19 minutes later at 8:13 AM on December 31.

The earliest sunset is 5:07 PM on December 8 and the latest sunset is 10 minutes later at 5:18 PM on December 31.

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

For reference, on June 20, the longest day of the year, the Sun rises at 6:03 AM and sets 15 hours, 22 minutes later, at 9:25 PM, while on December 21, the shortest day of the year, it rises at 8:10 AM and sets 9 hours, 0 minutes later, at 5:11 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 in Grand Rapids is essentially constant during December, remaining around 0% throughout.

For reference, on July 27, the muggiest day of the year, there are muggy conditions 36% of the time, while on November 15, 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 in Grand Rapids is essentially constant during December, remaining within 0.3 miles per hour of 12.1 miles per hour throughout.

For reference, on January 12, the windiest day of the year, the daily average wind speed is 12.6 miles per hour, while on August 2, the calmest day of the year, the daily average wind speed is 7.8 miles per hour.

The hourly average wind direction in Grand Rapids throughout December is predominantly from the west, with a peak proportion of 41% on December 13.

Grand Rapids 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 in Grand Rapids is decreasing during December, falling by 5°F, from 45°F to 40°F, over the course of the month.

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 Grand Rapids typically lasts for 5.5 months (167 days), from around April 28 to around October 12, rarely starting before April 10 or after May 17, and rarely ending before September 25 or after October 30.

The month of December in Grand Rapids is reliably fully outside of 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 Grand Rapids are essentially constant during December, remaining within 3°F of 2,930°F throughout.

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 Grand Rapids is essentially constant during December, remaining within 0.1 kWh of 1.4 kWh throughout.

The lowest average daily incident shortwave solar energy during December is 1.3 kWh on December 22.