Winter Weather in Morro Bay United States

Daily high temperatures are around 63°F, rarely falling below 55°F or exceeding 72°F. The lowest daily average high temperature is 62°F on December 23.

Daily low temperatures are around 46°F, rarely falling below 37°F or exceeding 54°F. The lowest daily average low temperature is 44°F on January 3.

For reference, on August 23, the hottest day of the year, temperatures in Morro Bay typically range from 56°F to 74°F, while on January 3, the coldest day of the year, they range from 44°F to 62°F.

The figure below shows you a compact characterization of the hourly average winter temperatures. 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.

Ovalle, Chile (5,589 miles away) is the far-away foreign place with temperatures most similar to Morro Bay (view comparison).

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The winter in Morro Bay experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 40% to 45%. The highest chance of overcast or mostly cloudy conditions is 46% on February 17.

The clearest day of the winter is December 1, with clear, mostly clear, or partly cloudy conditions 60% of the time.

For reference, on February 17, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 46%, while on August 23, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 92%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Morro Bay, the chance of a wet day over the course of the winter is rapidly increasing, starting the season at 15% and ending it at 22%.

For reference, the year's highest daily chance of a wet day is 24% on February 20, and its lowest chance is 0% on July 26.

Rainfall

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

The average sliding 31-day rainfall during the winter in Morro Bay is rapidly increasing, starting the season at 1.6 inches, when it rarely exceeds 3.5 inches or falls below 0.2 inches, and ending the season at 2.8 inches, when it rarely exceeds 5.9 inches or falls below 0.3 inches.

The highest average 31-day accumulation is 2.9 inches on February 16.

Over the course of the winter in Morro Bay, the length of the day is rapidly increasing. From the start to the end of the season, the length of the day increases by 1 hour, 28 minutes, implying an average daily increase of 59 seconds, and weekly increase of 6 minutes, 56 seconds.

The shortest day of the winter is December 21, with 9 hours, 46 minutes of daylight and the longest day is February 28, with 11 hours, 24 minutes of daylight.

The latest sunrise of the winter in Morro Bay is 7:12 AM on January 6 and the earliest sunrise is 39 minutes earlier at 6:33 AM on February 28.

The earliest sunset is 4:50 PM on December 4 and the latest sunset is 1 hour, 8 minutes later at 5:58 PM on February 28.

Daylight saving time is observed in Morro Bay during 2024, but it neither starts nor ends during the winter, so the entire season is in daylight saving time.

For reference, on June 20, the longest day of the year, the Sun rises at 5:48 AM and sets 14 hours, 33 minutes later, at 8:21 PM, while on December 21, the shortest day of the year, it rises at 7:08 AM and sets 9 hours, 46 minutes later, at 4:54 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 the winter of 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 Morro Bay is essentially constant during the winter, remaining around 0% throughout.

For reference, on July 5, 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 in Morro Bay is gradually increasing during the winter, increasing from 8.5 miles per hour to 9.0 miles per hour over the course of the season.

For reference, on May 23, the windiest day of the year, the daily average wind speed is 10.0 miles per hour, while on September 15, the calmest day of the year, the daily average wind speed is 7.5 miles per hour.

The hourly average wind direction in Morro Bay throughout the winter is predominantly from the north, with a peak proportion of 46% on December 1.

Morro Bay 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 Morro Bay is gradually decreasing during the winter, falling by 2°F, from 58°F to 55°F, over the course of the season.

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).

Temperatures in Morro Bay are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

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 Morro Bay are very rapidly decreasing during the winter, decreasing by 2,749°F, from 3,020°F to 272°F, over the course of the season.

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 Morro Bay is increasing during the winter, rising by 1.5 kWh, from 2.9 kWh to 4.4 kWh, over the course of the season.

The lowest average daily incident shortwave solar energy during the winter is 2.6 kWh on December 23.

For the purposes of this report, the geographical coordinates of Morro Bay are 35.366 deg latitude, -120.850 deg longitude, and 59 ft elevation.

The topography within 2 miles of Morro Bay contains significant variations in elevation, with a maximum elevation change of 748 feet and an average elevation above sea level of 88 feet. Within 10 miles contains significant variations in elevation (2,762 feet). Within 50 miles contains large variations in elevation (4,314 feet).

The area within 2 miles of Morro Bay is covered by water (28%), artificial surfaces (28%), grassland (19%), and herbaceous vegetation (18%), within 10 miles by water (36%) and grassland (35%), and within 50 miles by water (43%) and grassland (33%).