A 20F Difference Across Mission Bay

Image: NWS San Diego

San Diegans know their city is notorious for its microclimates. The combination of mountains, valleys, canyons and mesas that dot the surface are often responsible for these interesting weather patterns. In the Fall 2019, the National Weather Service (NWS) in San Diego picked up one of the most extreme head-scratching examples of a microclimate: a 20°F temperature difference from one side of Mission Bay to the other.

On October 24, 2019, the NWS recorded 71°F near Mission Blvd. while a monitoring station near Interstate 5 recorded 91°F, two locations less than 3 miles (4.5km) apart.

How could two locations within view of one another have such drastic temperature differences? Is this a location you would expect to find a microclimate? Why or why not?

What questions can we ask to learn more about this phenomenon?

• What is the average temperature difference of these two locations?
• How does this October 24 instance differ from the average?
• This phenomenon occurred during the fall. Did something similar ever happen during one of the other seasons?
• What was happening over the ocean to the west? What was happening over the mountains to the east?
• What happens when cold air meets warm air? What is happening weather-wise in the middle of Mission Bay?

Resources:

WaterNewsNetwork, San Diego’s Six CIMIS Climate Zones

Leonard Perry, University of Vermont: Microclimates: What Do They Mean To You?