Castle Rock Air Quality Forecast - Today, Tomorrow
Air Quality Today
Today (10 October): Air quality in Castle Rock is moderate. AQI, NO2, and O3 are moderate; PM2.5 is fair; PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 12:00 PM (O3: 50.8/100).
Air Quality Tomorrow
Tomorrow (11 October 2026): Air quality in Castle Rock is poor. AQI worsens to poor; NO2 decreases to fair; O3 increases to poor; all other pollutants stay as today. Pollution peaks around 2:00 PM (O3: 60.8/100).
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Air Quality
Today - 10 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Moderate | 50.8/100 |
| PM2.5 (fine particles) | Fair | 28.6/100 |
| PM10 (coarse particles) | Good | 13.6/100 |
| NO2 (nitrogen dioxide) | Moderate | 46.5/100 |
| O3 (ozone) | Moderate | 50.8/100 |
| SO2 (sulfur dioxide) | Good | 0.9/100 |
| CO (carbon monoxide) | Good | 0.6/100 |
| HCHO (formaldehyde) | Good | 1.9/100 |
| PM1 (ultrafine particles) | Good | 3.6/100 |
Tomorrow - 11 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Poor | 60.8/100 |
| PM2.5 (fine particles) | Fair | 35.1/100 |
| PM10 (coarse particles) | Good | 16.5/100 |
| NO2 (nitrogen dioxide) | Fair | 38.0/100 |
| O3 (ozone) | Poor | 60.8/100 |
| SO2 (sulfur dioxide) | Good | 1.7/100 |
| CO (carbon monoxide) | Good | 0.6/100 |
| HCHO (formaldehyde) | Good | 2.9/100 |
| PM1 (ultrafine particles) | Good | 7.0/100 |
Local Environmental Conditions
Around the heart of Castle Rock, a mix of built-up land and open space means traffic is an important, but not overwhelming, local pollution source. At around 1,920 m above sea level, the air is generally well mixed, though calm, cold nights can trap smoke near the ground. Local sources include traffic on I-25. Home heating, especially wood stoves and fireplaces, adds smoke and fine particles in the colder months.
Particle levels tend to be highest from November to April, when home heating and traffic add more emissions and cold, calm spells at around -1°C slow their dispersal. By contrast, summer sun from July to August cooks traffic fumes into ozone, especially in the warmest month, which averages 23°C. Stronger winds around February, about 15 km/h on average, usually bring some of the cleanest air of the year.
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Frequently Asked Questions About Air Quality in Colorado
Is air quality bad in Castle Rock right now?
On 10 October 2026, overall air quality in Castle Rock is moderate. AQI is the main air quality indicator at 50.8/100. Pollution peaks around 12:00 PM (O3: 50.8/100).
Will air quality be worse tomorrow in Castle Rock?
On 11 October 2026, air quality conditions in Castle Rock will be worse than today, with AQI forecast at poor at 60.8/100. Pollution peaks around 2:00 PM (O3: 60.8/100).
When is air pollution at its worst in Castle Rock?
Particle levels tend to be highest from November to April, when home heating and traffic add more emissions and cold, calm spells at around -1°C slow their dispersal. By contrast, summer sun from July to August cooks traffic fumes into ozone, especially in the warmest month, which averages 23°C. Stronger winds around February, about 15 km/h on average, usually bring some of the cleanest air of the year.
Are air quality levels in Castle Rock based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
Understanding the Scale
The 0–100 air quality scores represent risk levels, not direct air pollutant concentrations. Higher scores indicate higher risk.
Air Quality
| Good | 0-20 | Low air quality risk. Air quality is expected to be good, with low levels of pollution. |
| Fair | 20-40 | Generally low air quality risk. Air quality is expected to be acceptable, with some pollution present. |
| Moderate | 40-60 | Moderate air quality risk. Air pollution is elevated and air quality may be less favorable. |
| Poor | 60-80 | High air quality risk. Air pollution is high and air quality is expected to be poor. |
| Very Poor | 80-100 | Very high air quality risk. Air pollution is very high and air quality is expected to be very poor. |