Downey's weather features a typical Southern California Mediterranean climate.

There are many clear days throughout the year, with low precipitation, and extreme cold or heavy snowfall is rare. In winter (December to February), daytime highs are around 15 to 18 degrees Celsius, which is comfortable with just a coat. While temperatures can drop below 10 degrees in the mornings and evenings, it is a different kind of mildness compared to winters in the East. Those who have just moved from Korea may initially feel like there is 'no winter.'

Summer (June to September) can be somewhat tricky. Between July and September, temperatures often fluctuate between 33 and 38 degrees Celsius, and due to the characteristics of the LA basin, the combination of summer smog and the heat island effect can make it feel even hotter. Downey is located about 15 to 20 miles inland from the coast, so it does receive some cooling effect from the ocean breeze, but it is not as cool as coastal cities (Long Beach, Santa Monica). There will definitely be days when it is hard to endure without air conditioning, so be sure to check the cooling system of your home or apartment before moving.

Spring (March to May) and fall (October to November) are the most pleasant seasons in Downey. Daytime temperatures are stable around 20 to 26 degrees, with low precipitation and relatively clean air. The annual precipitation is about 14 inches (355 mm), which is less than half of that in Korea. Therefore, there is a culture of being mindful of drought and conserving water throughout California.

Wildfire smoke mainly affects the area during the dry season from August to November when wildfires occur. While Downey itself is not mountainous, smoke from nearby areas (Angeles National Forest, near San Gabriel Valley) can quickly raise the AQI (Air Quality Index) when carried by the wind.

Developing a habit of regularly monitoring air quality with apps like IQAir or AirNow can be beneficial for health management. Overall, the weather is generally pleasant for living, but it is wise to prepare in advance for summer heat and wildfire smoke periods.