Kicking off with “weather LA in December,” this month marks a fascinating time in the City of Angels, where mild temperatures give way to cooler weather and the possibility of precipitation. The LA region is known for its varied climate, but December stands out for its unique blend of seasonal changes.
Few months are as captivating as December in LA, a place where weather patterns are shaped by the interplay of high and low-pressure systems, temperature fluctuations, and precipitation events. The influence of the California Current plays a crucial role in modulating weather conditions during this time, making December an essential part of LA’s meteorological calendar.
Weather Patterns in Los Angeles During December
Los Angeles, a city known for its mild climate, experiences a significant change in weather during the month of December. As the Northern Hemisphere enters its winter season, LA begins to feel the effects of the changing climate, with cooler temperatures and increased precipitation.
Typical High and Low-Pressure Systems
Los Angeles is influenced by two primary high-pressure systems during December: the Azores High and the North Pacific High. The Azores High, located in the North Atlantic Ocean, is a semi-permanent high-pressure system that plays a significant role in shaping the city’s weather. It creates a dry and stable air mass that moves toward LA, resulting in clear skies and mild temperatures. In contrast, the North Pacific High, located in the Northern Pacific Ocean, is a temporary high-pressure system that develops near the California coast during the winter months. It brings cooler air from the Pacific Ocean, leading to increased precipitation and cloudy skies.
Average Temperature and Precipitation
The average temperature in Los Angeles during December is around 57°F (14°C), with high temperatures often reaching the mid-60s (18-20°C) and low temperatures dipping into the mid-40s (7-9°C). December is also the wettest month in LA, with an average of 3.3 inches (84 mm) of precipitation. This is significantly higher than the average precipitation seen during the rest of the year.
Formation of Low-Pressure Systems
Low-pressure systems that bring rain to LA during December typically form over the Pacific Ocean, where the cold air from the North Pacific High meets the warmer air from the subtropics. As the two air masses interact, they create a low-pressure system that moves toward the coast, resulting in precipitation. The formation of these low-pressure systems is also influenced by the California Current, a cold-water current that flows along the California coast.
Significance of the California Current
The California Current plays a crucial role in modulating the weather in LA during December. As the cold water from the North Pacific flows along the coast, it cools the air above it, leading to increased precipitation and cloudy skies. The California Current also helps to regulate the temperature in LA, keeping it relatively mild compared to other parts of the country. Without the California Current, the temperatures in LA would likely be much lower, resulting in a harsher winter climate.
Precipitation in December is caused by the interaction of cold air from the North Pacific High and warm air from the subtropics.
- The Azores High and the North Pacific High are two primary high-pressure systems that influence the weather in LA during December.
- The North Pacific High brings cooler air from the Pacific Ocean, resulting in increased precipitation and cloudy skies.
- The California Current plays a crucial role in modulating the weather in LA, cooling the air above it and regulating the temperature.
| Month | High Temperature (°F) | Low Temperature (°F) | Precipitation (inches) |
|---|---|---|---|
| December | 66°F | 48°F | 3.3 inches |
| January | 64°F | 45°F | 2.8 inches |
| February | 65°F | 45°F | 2.6 inches |
Temperature Fluctuations in Los Angeles During December
Temperature fluctuations in Los Angeles during December can be quite significant, with average highs ranging from 68°F (20°C) to 73°F (23°C), while lows can dip to around 47°F (8°C) to 52°F (11°C).
This temperature variation can have a noticeable impact on various sectors of society in LA, including agriculture, transportation, and recreation. In terms of agriculture, the fluctuating temperatures can affect the growth and development of crops, which may require additional care and attention from farmers to mitigate the effects of temperature fluctuations. Additionally, temperature changes can also impact the distribution and availability of certain produce, which may affect the local food supply and economy.
Economic Impact of Temperature Fluctuations
Temperature fluctuations in Los Angeles can also have an economic impact, particularly on industries related to tourism and recreation. The mild winter weather in LA attracts many tourists from colder regions, who come to enjoy the city’s mild climate and outdoor recreational activities. However, temperature fluctuations can disrupt these plans, leading to a decline in tourism revenue. For example, a sudden cold snap or heat wave can force tourists to alter their plans, resulting in lost revenue for local businesses.
- Impact on Tourism Revenue:
- A 10°F (5.5°C) drop in temperature can result in a 20% decline in tourism revenue, as tourists are less likely to visit LA during colder periods.
- A 10°F (5.5°C) increase in temperature can lead to a 15% increase in tourism revenue, as tourists are more likely to visit LA during warmer periods.
- Impact on Transportation:
- Temperature fluctuations can lead to an increase in traffic congestion, as drivers may need to slow down to navigate icy or wet roads.
- Additionally, temperature changes can cause roads to become slippery, leading to an increase in accidents and vehicle damage.
Cold and Warm Anomaly Factors
The factors that contribute to colder or warmer temperature anomalies in Los Angeles during December can be attributed to various weather patterns. Cold anomalies can be caused by a high-pressure system located over the eastern Pacific Ocean, which can push cold air from the Arctic towards the West Coast. On the other hand, warm anomalies can be caused by a low-pressure system located over the eastern Pacific Ocean, which can bring warm air from the subtropics towards the West Coast.
- Cold Anomaly Factors:
- A high-pressure system located over the eastern Pacific Ocean can push cold air from the Arctic towards the West Coast.
- The presence of a strong jet stream can also contribute to cold anomalies, as it can bring cold air from the Arctic towards the West Coast.
- Warm Anomaly Factors:
- A low-pressure system located over the eastern Pacific Ocean can bring warm air from the subtropics towards the West Coast.
- The presence of a strong El Niño event can also contribute to warm anomalies, as it can bring warm air from the subtropics towards the West Coast.
Impact on Local Events and Festivals
Temperature fluctuations in Los Angeles can also impact local events and festivals, such as the LA County Fair and the Downtown LA Farmers’ Market. The mild winter weather in LA makes it an ideal time for outdoor events and festivals, but temperature fluctuations can disrupt these plans. For example, a sudden cold snap or heat wave can force event planners to alter their plans, resulting in lost revenue and inconvenience to attendees.
Precipitation and Snowfall in Los Angeles During December
Los Angeles, known for its year-round Mediterranean climate, experiences a significant decrease in precipitation during December. However, this slight decrease does not guarantee the absence of rainfall in the region.
Historical Data on Precipitation and Snowfall in LA
Los Angeles receives an average of 0.64 inches (16.3 mm) of precipitation in December, which accounts for only 3% of the region’s annual precipitation. Over the past 30 years, the city has experienced varying levels of precipitation during this month, with fluctuations in the range of 0.25 inches (6.4 mm) and 2.01 inches (51.1 mm). Notably, snowfall in Los Angeles is an extremely rare occurrence, with no snow recorded in the downtown area since 1962.
Role of Atmospheric Conditions in Influencing Precipitation in LA
Moisture content in the atmosphere largely determines the likelihood of precipitation in Los Angeles during December. The region’s proximity to the Pacific Ocean means that moisture from the ocean often leads to cloud formation, which can result in precipitation. However, strong high-pressure systems dominate the region during this time, suppressing the formation of clouds and precipitation. Wind patterns also play a crucial role, as southerly winds can bring warm, moist air from the Gulf of California, while northerly winds can bring cooler, drier air from the desert regions.
Average Annual Precipitation in the LA Region
Los Angeles experiences an average annual precipitation of 12.2 inches (310.9 mm), with the majority occurring between December and February. When comparing the average annual precipitation to the December amount, it becomes clear that December accounts for less than 5% of the region’s annual precipitation. Understanding these patterns is essential for agricultural planning, water management, and overall climate modeling.
Average Monthly Precipitation in LA from December to February
| Month | Average Precipitation (inches) |
|---|---|
| December | 0.64 |
| January | 1.43 |
| February | 1.67 |
The table illustrates that the average monthly precipitation in the LA region significantly increases during the winter months, highlighting the potential for snowfall and heavy rainfall in the surrounding mountains.
Comparison of Precipitation Patterns
A closer analysis of precipitation patterns in the LA region reveals a high degree of variability from year to year. While some years experience above-average rainfall, others see drought-like conditions. Therefore, accurate forecasting and understanding of atmospheric conditions are crucial for predicting precipitation in this region.
Wind Patterns in Los Angeles During December: Weather La In December
During December, Los Angeles experiences a distinct pattern of winds that shape its weather and climate. The region’s proximity to the Pacific Ocean and its coastal location create a unique wind system that plays a significant role in dispersing heat and moisture, affecting temperature and precipitation.
Prevailing Wind Directions in December
The prevailing wind directions in LA during December are northerly and easterly winds, which are driven by the high-pressure system that dominates the Great Basin region. These winds bring cooler and drier air from the north, resulting in a decrease in temperatures and humidity levels. The northerly winds also contribute to the formation of temperature inversions, which can further exacerbate air pollution levels in the region.
The northerly winds bring cooler air from the north, resulting in a significant decrease in temperatures.
Impact on Air Pollution and Temperature
The wind patterns in LA during December have a significant impact on air quality and temperature. The northerly and easterly winds help to disperse pollutants and particulate matter, reducing air pollution levels. Additionally, the cooler temperatures brought by these winds can contribute to a decrease in the formation of ground-level ozone, a major component of smog. However, the wind patterns can also lead to an increase in PM2.5 levels, as the cooler air can stagnate near the surface, trapping pollutants and particulate matter.
Role of Wind Patterns in Dispersing Heat and Moisture
The wind patterns in LA during December play a crucial role in dispersing heat and moisture, affecting temperature and precipitation. The northerly and easterly winds help to disperse the heat from the desert regions, reducing temperatures and humidity levels. Additionally, the winds help to drive moisture from the Pacific Ocean into the region, resulting in increased precipitation and cloud cover.
Types of Storms that Can Affect LA During December
During December, LA can experience a variety of storms, including cold fronts, winter storms, and atmospheric rivers. These storms can bring significant precipitation, wind, and temperature changes to the region. The wind patterns in LA during December can influence the behavior of these storms, causing them to track farther inland or resulting in more intense precipitation.
Notable Wind Event in December
One notable wind event in December that impacted LA’s weather was the Christmas Storm of 2010. This storm brought heavy rain, strong winds, and widespread power outages to the region. The strong northerly winds contributed to the formation of a temperature inversion, leading to a significant decrease in temperatures and an increase in air pollution levels. The storm also resulted in significant precipitation, with some areas receiving over 2 inches of rain.
Fog and Cloud Cover in Los Angeles During December
Los Angeles in December is a city shrouded in mist, with fog and cloud cover dominating the skies. This phenomenon is a result of the region’s unique geographical and climatic conditions.
Factors Contributing to Fog and Cloud Cover
Fog and cloud cover in the LA region during December are influenced by a combination of temperature, humidity, and wind patterns. The cold temperatures of the winter season lead to a decrease in the air’s capacity to hold moisture, resulting in the formation of fog. Additionally, the moist air from the Pacific Ocean collides with the cool air from the land, creating a layer of fog that can persist for several days. Wind patterns also play a significant role, as the prevailing northwesterly winds can disperse the fog and create clearer skies.
Comparison to Other Months
Fog and cloud cover in December are more frequent and persistent compared to other months. The table below highlights the average cloud cover and fog frequencies in LA during December.
| Month | Average Cloud Cover (%) | Average Fog Frequency (days) |
|---|---|---|
| December | 64% | 10.5 |
| January | 57% | 8.2 |
| February | 56% | 7.5 |
| Average | 59% | 8.7 |
Effects on Traffic, Commute Times, and Outdoor Activities
Fog and cloud cover in the LA region during December have significant impacts on daily life. Traffic congestion and commute times are often disrupted due to low visibility, leading to increased travel time and frustration. Outdoor activities such as hiking, surfing, and golfing are also affected, as the fog and cloud cover can reduce visibility and make it difficult to participate in these activities. However, the fog also provides a unique opportunity for photographers to capture stunning images of the city shrouded in mist.
Impact on Outdoor Activities
The fog and cloud cover in the LA region during December have a significant impact on various outdoor activities, including:
- Hiking: Fog and cloud cover can reduce visibility, making it difficult to navigate trails and increasing the risk of accidents.
- Surfing: The fog and cloud cover can create an eerie atmosphere on the beach, but it also reduces visibility and makes it challenging to spot hazards such as riptides.
- Golfing: The fog and cloud cover can make it difficult for golfers to see the ball and the green, leading to increased risk of accidents and lost balls.
Photographic Opportunities
The fog and cloud cover in the LA region during December provide a unique opportunity for photographers to capture stunning images of the city shrouded in mist. The soft, diffused light creates a captivating atmosphere, and the fog adds an extra layer of mystique to the city’s skyline.
“Fog is not just a weather phenomenon; it’s a mood, a feeling, a sensation.”
Holiday-Induced Weather Events in Los Angeles
Los Angeles is known for its mild Mediterranean climate, making it an ideal destination for holiday celebrations. However, during the winter months, the city can experience various weather-related hazards that impact holiday events and festivities. From heatwaves to winter storms, LA’s unique climate makes it challenging to predict and prepare for the unexpected.
Types of Weather-Related Hazards During the Holiday Season
The holiday season in Los Angeles, December, can bring various types of weather-related hazards. These include heatwaves, droughts, winter storms, and even Santa Ana winds. Heatwaves, for instance, can occur when high-pressure systems move over the region, bringing clear skies and warm temperatures. Prolonged heatwaves can have severe impacts on holiday events, especially outdoor ones, and can even affect air quality.
Notable Weather Events During December
December is known for its variable weather patterns in Los Angeles. The month can bring both rain and sunshine, making it challenging for event planners to prepare for holidays. Some notable weather events during December include the El Niño effect, where warmer ocean waters off the coast of South America impact the jet stream, leading to heavy rainfall and flooding. On the other hand, LA can also experience droughts, where the lack of rainfall and precipitation impacts the region’s water supply. The droughts can be particularly challenging during the holiday season, affecting the city’s Christmas tree supply and forcing residents to get creative with decorations.
The Importance of Weather Forecasting and Preparedness, Weather la in december
Weather forecasting and preparedness are crucial during the holiday season in Los Angeles. The city’s unique climate makes it challenging to predict the weather, but advanced forecasting tools and technologies can help mitigate the effects of severe weather events. The National Weather Service (NWS), for example, issues weather alerts and warnings in real-time, keeping residents informed and prepared for the latest weather developments. Additionally, LA’s emergency management officials work closely with event planners and public safety agencies to ensure that holiday events are staged safely and effectively.
The Impact of Weather on LA’s Local Economy During the Holiday Season
Weather-related hazards can have a significant impact on LA’s local economy during the holiday season. Prolonged heatwaves, for instance, can lead to reduced tourist traffic and lower sales for retailers, while heavy rainfall and flooding can disrupt outdoor holiday events and impact local businesses. According to a study by the Los Angeles Economic Development Corporation, every dollar in federal funding for disaster relief and preparedness generates up to $15 in economic returns. Investing in weather forecasting and preparedness, therefore, can have significant economic benefits for the city and its residents.
- The economic benefits of investing in weather forecasting and preparedness can be substantial, with every dollar generating up to $15 in economic returns.
- The city’s emergency management officials work closely with event planners and public safety agencies to ensure that holiday events are staged safely and effectively.
- Notable weather events during December include the El Niño effect, where warmer ocean waters off the coast of South America impact the jet stream, leading to heavy rainfall and flooding.
- Heatwaves can have severe impacts on holiday events, especially outdoor ones, and can even affect air quality.
Final Summary
As LA enters a new season of cool wonders, it’s essential to stay aware of the city’s weather patterns, from the formation of low-pressure systems to the effects of temperature fluctuations on daily life. With an understanding of these dynamic forces, you can better navigate the city and make the most of its diverse offerings, whether you’re a resident, visitor, or simply a weather enthusiast.
Helpful Answers
What is the average high and low temperature in LA during December?
The average high temperature in LA during December is around 64°F (18°C), while the average low temperature is around 51°F (11°C).
How much precipitation can LA expect in December?
On average, LA receives around 3.2 inches (81 mm) of precipitation in December, with most of it falling as rain rather than snow.
Can snow fall in LA in December?
While snow is not uncommon in LA’s surrounding mountains, significant snowfall is rare in the city itself. However, LA has experienced light snow on a few instances in December over the years.
