What hourly AQI reveals : Rainfall’s Limited Impact on Delhi NCR’s Air Quality

January 2026 saw Delhi NCR record one of its wetter winter spells in recent years. According to the India Meteorological Department (IMD), the city received 24 mm of rainfall by January 28, making it the wettest January since 2022. A major share of this rain fell on January 23, raising expectations of air quality improvement. 

However, hourly AQI data sourced from AQI.in from 21st to 28th January, 2026 for Delhi NCR shows that the relief was brief and uneven for the past week.

AQI Trend for the Fourth Week of January, 2026 

How Rainfall on January 23 Impacted Air Quality 

The January 23 rainfall event delivered 19.8 mm of rain to Delhi, produced the clearest improvement in air quality during the week. Within hours of the rainfall, AQI levels across Delhi, Noida, and Gurgaon dropped sharply. 

Hourly data shows AQI values briefly falling to 50 to 70 on 24th January pushing AQI into the Moderate category. This improvement was visible across the entire NCR, indicating a region-wide washout of particulate matter rather than a localized effect.

However, the impact was short-lived. Within 6-10 hours, AQI levels began rising again, crossing 300 and returning to the Poor to Very Poor range by the following day.

Why the January 27 Rain Barely Helped

A second rainfall event occurred on January 27, but its impact on air quality was negligible. IMD data indicates that this spell produced trace to very light rainfall, and stood at 4.2mm at Safdarjung.

Hourly AQI trends show no meaningful dip following this event. Pollution levels remained largely unchanged, continuing in the Poor to Very Poor category across Delhi NCR. The contrast between January 23 and January 27 highlights an important insight: light rainfall lacks the intensity and duration needed to remove accumulated winter pollution

Current Air Quality Status in Delhi NCR

As of the end of January, Delhi NCR continues to experience Poor to Very Poor air quality, according to hourly data from AQI.in . While brief improvements occur during favorable weather windows, pollution levels rise quickly once rain stops.

IMD’s winter climatology explains this pattern. Low wind speeds, strong temperature inversions, and shallow mixing heights trap pollutants near the surface, allowing emissions to accumulate rapidly despite rainfall.

Conclusion

January 2026 clearly demonstrates that rain is not a reset button for Delhi NCR’s air. While rainfall can provide momentary relief, the impact is fleeting unless accompanied by sustained winds or prolonged precipitation. The rapid rebound seen in hourly AQI data underscores why weather-driven improvements alone cannot solve the underlying winter conditions or emission patterns that drive high AQI in Delhi NCR.

In effect, January’s rainfall offered proof of possibility, not a permanent fix. It demonstrated what cleaner air could look like, but also how quickly those gains are lost without sustained meteorological support or emission reduction.

Check your local AQI regularly on AQI.in and stay updated.