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Cooling degree days (CDDs) are useful for approximating air conditioning demand ❄️, both in current and future climates. They are calculated by comparing the daily average temperature to a base temperature, typically 65°F (18.3°C). CDDs help us understand the extent to which outside temperatures surpass a comfortable threshold, thereby indicating the need for air conditioning.

Here are some takeaways related to CDDs for San Diego County:

🌡️ In about 15 years (2040), an average year will require more cooling than an average year from the recent past. This will increase cooling costs 💰(all else being equal)

🌡️ Inland communities in San Diego County that are already the warmest, like Santee, El Cajon, and La Mesa will have the largest absolute increase in CDDs

🌡️ Coastal communities on the Pacific Ocean, like Del Mar and Imperial Beach, will still continue to benefit from Nature’s air conditioner and may not require added cooling on most days (the exception being the occasional heat wave 🔥)

Look at 580 x 300 getting some love.
Look at 580 x 300 getting some love.

Source: Cal-Adapt; Recently, Cal-Adapt has released 1000s of terabytes of high resolution climate model output for California, including ERA5 reanalysis, dynamically downscaled to 3-km with WRF. This dataset offers unique insight into the many micro-climates of California, including places where no in situ observations exist.

Figures created using #xarray, #dask, #geopandas, and #cartopy. City boundaries are from the U.S. Census Bureau.

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