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Los Angeles has one of the most pleasant climates in the world for ventilation on paper — mild year-round temperatures (18–28°C daily range) and low humidity especially inland. The marine layer that rolls in from the Pacific most evenings creates natural cooling: opening windows after sunset brings fresh, cool ocean air on most evenings from May through October.
However, LA's air quality is the dominant factor in the OpenWindow.live recommendation. The South Coast Air Quality Management District monitors over 30 stations across the basin. Smog alerts still occur regularly, particularly in the San Fernando Valley and Inland Empire. During wildfire season (October–November), AQI can reach "Hazardous" levels across the entire metro area within hours.
The practical rule for LA: check the AQI before the temperature. A 22°C evening with AQI 150 from wildfire smoke is far worse for indoor air quality than a 28°C afternoon with AQI 30. OpenWindow.live weighs both automatically in its recommendation.
In August, the warmest month in Los Angeles, afternoons reach 32 °C (89 °F) on average and nights fall to 18 °C (64 °F). The coolest air arrives between 05:00 and 08:00 (18 °C (65 °F) on average): that is when opening the windows cools the home fastest.
Fine particles (PM2.5) are usually lowest around 17:00 (16 µg/m³) and highest around 01:00 (26 µg/m³).
| Month | Avg high | Avg low | Humidity | Coolest hours | PM2.5 |
|---|---|---|---|---|---|
| January | 19 °C | 8 °C | 61% | 06:00–09:00 | 26 |
| February | 20 °C | 8 °C | 61% | 06:00–09:00 | 22 |
| March | 20 °C | 9 °C | 67% | 05:00–08:00 | 21 |
| April | 24 °C | 11 °C | 63% | 04:00–07:00 | 22 |
| May | 25 °C | 13 °C | 67% | 03:00–06:00 | 16 |
| June | 28 °C | 15 °C | 67% | 04:00–07:00 | 16 |
| July | 31 °C | 17 °C | 66% | 04:00–07:00 | 17 |
| August | 32 °C | 18 °C | 65% | 05:00–08:00 | 21 |
| September | 31 °C | 18 °C | 68% | 05:00–08:00 | 18 |
| October | 27 °C | 15 °C | 63% | 05:00–08:00 | 24 |
| November | 23 °C | 11 °C | 56% | 06:00–09:00 | 23 |
| December | 19 °C | 9 °C | 67% | 06:00–09:00 | 25 |
Data: Open-Meteo historical archive, hourly averages 2021–2025 (air quality 2023–2025), local time.
How to air your home in winter in Los Angeles without condensation and mould →
In Los Angeles, the best ventilation times are typically early morning (5–8 AM) and late evening (after sunset) when outdoor temperatures drop below indoor levels.
Yes, in most weather conditions. Open windows can drop indoor temperature by 2–5°C in 30 minutes if outdoor air is cooler. Check the live recommendation above for tonight.
Above 80% humidity, opening windows can make indoor air feel sticky. Combine with dehumidifier or wait for drier hours.