Hosur — Seasonal Pollution Patterns
Month-by-month air quality patterns for Hosur across 1 years of CPCB data. Based on CPCB station data, 2016–present.
Tamil Nadu · Live Hosur AQI →
At a glance
Based on 1 years of CPCB monitoring across 1 stations, Hosur averages AQI 90 annually, with a pronounced seasonal pattern classified as flat year-round. The worst month is December at AQI 109 (Moderate) and the cleanest is August at AQI 55 (Satisfactory) — a 54-point swing between them. Severe days (AQI > 400) make up 0% of the record while Good-or-Satisfactory days account for 73.9%.
The four seasons
Indian meteorological seasons: Winter (Dec–Feb), Summer (Mar–May), Monsoon (Jun–Sep), Post-monsoon (Oct–Nov).
Winter
AQI 109Summer
AQI 0Monsoon
AQI 72Post-monsoon
AQI 91Climograph — monthly averages and Poor+ days
Bars show the long-run AQI average per month. The overlay line counts days in Poor, Very Poor or Severe bands.
Year × month heatmap
One cell per year-month combination.
Each cell = monthly average AQI for that year-month combination. Row averages on the right, column averages at the bottom.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Avg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2022 | — | — | — | — | — | — | — | 55 | 81 | 94 | 87 | 109 | 90 |
| Avg | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 55 | 81 | 94 | 87 | 109 | — |
Winter in Hosur
Winter (Dec–Jan–Feb) in Hosur averages AQI 109 across 27 measured days — Moderate on the NAQI scale. 0% of those days fall in Very Poor or Severe; 37% are Good or Satisfactory. Winter in Hosur is not the headline season, but shallow morning inversions can still produce short spikes. Hosur's cleanest months lie elsewhere in the calendar, so the winter response is less about evacuation than about protecting sensitive groups on the worst individual days.
Diwali, stubble burning and the monsoon
Three India-specific signatures that shape the seasonal curve.
Diwali week impact
The 7-day window around Diwali averages AQI 124 (Moderate), versus 82 (Satisfactory) for the rest of October. 6 sampled days across the CPCB record.
Stubble-burning window (Oct 15 – Nov 15)
In-window severe-day share 0% vs 0% outside the window. The difference is a direct signal of upwind crop-residue transport.
Monsoon cleansing (Jul 15 – Sep 15)
Core monsoon window averages AQI 62 (Satisfactory), compared with an annual mean of 90.
Summer
Summer (Mar–Apr–May) in Hosur averages AQI 0 across 0 measured days — Good on the NAQI scale. 0% of those days fall in Very Poor or Severe; 0% are Good or Satisfactory. Summer air in Hosur is shaped by a very different mix of forces. Rising temperatures drive deeper vertical mixing which dilutes local emissions, but pre-monsoon dust storms, wildfires and heat-accelerated ozone formation can all push AQI higher on individual days. Hosur's summer mean of 0 is the lighter side of the year for outdoor activity, though hot afternoons can still irritate sensitive airways.
Monsoon
Monsoon (Jun–Jul–Aug–Sep) in Hosur averages AQI 72 across 31 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 96.8% are Good or Satisfactory. The Jul 15 – Sep 15 core monsoon window averages AQI 62, a 31.1% improvement on the annual mean of 90. Rain scrubs particulates out by wet deposition, and the deeper monsoon boundary layer disperses what remains vertically. Short-lived rebounds can happen between spells of rain, but the overall pattern is strongly favourable for outdoor activity. For anyone with asthma or heart conditions, monsoon is the easy-breathing stretch of the year in Hosur.
Post-monsoon
Post-monsoon (Oct–Nov) in Hosur averages AQI 91 across 38 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 81.6% are Good or Satisfactory. Diwali and the three days either side of it average AQI 124 — 1.52× the normal October baseline of AQI 82 for Hosur, a spike of 42 points. Post-monsoon in Hosur is the handoff from clean monsoon air to the winter peak, and the transition is rarely gentle.
Month-by-month trajectories
How each month has moved across the 1-year CPCB record.
Daily calendar heatmap
Every measured day for the last 1 years. Expand for the full 1-year archive.
Month-by-month deep dive
Tap any month to expand.
Jan—+0%
No data for this month.
Feb—+0%
No data for this month.
Mar—+0%
No data for this month.
Apr—+0%
No data for this month.
May—+0%
No data for this month.
Jun—+0%
No data for this month.
Jul—+0%
No data for this month.
Aug2022–2022Latest AQI 55+0%
Aug in Hosur averages AQI 55 (Satisfactory) in the most recent year, having moved from 55 in 2022. Direction: stable (+0.0%).
Sep2022–2022Latest AQI 81+0%
Sep in Hosur averages AQI 81 (Satisfactory) in the most recent year, having moved from 81 in 2022. Direction: stable (+0.0%).
Oct2022–2022Latest AQI 94+0%
Oct in Hosur averages AQI 94 (Satisfactory) in the most recent year, having moved from 94 in 2022. Direction: stable (+0.0%).
Nov2022–2022Latest AQI 87+0%
Nov in Hosur averages AQI 87 (Satisfactory) in the most recent year, having moved from 87 in 2022. Direction: stable (+0.0%).
Dec2022–2022Latest AQI 109+0%
Dec in Hosur averages AQI 109 (Moderate) in the most recent year, having moved from 109 in 2022. Direction: stable (+0.0%).
Cities with similar (and opposite) seasonal profiles
Ranked by cosine similarity of 12-month AQI signatures across monitored Indian cities.
What to do with this information
If you are choosing when to visit Hosur or plan outdoor events — marathons, weddings, school sports, outdoor festivals — the CPCB record says August and the two adjacent months are the lowest-risk window. Daily variability still matters; check the live AQI page before committing on any specific date. Sensitive groups should treat December in Hosur as an indoor-air-priority month: close windows on high-AQI evenings, run a purifier with a HEPA filter rated for your room size, and reserve outdoor exercise for clear-weather mornings. On days above AQI 300, even healthy adults benefit from well-fitted N95 or KN95 masks for outdoor commutes.
Frequently asked questions
Which is the most polluted month in Hosur?
December is the most polluted month in Hosur on average, with a long-run AQI of 109 — firmly in the Moderate band. This is drawn from 1 CPCB monitoring stations across 1 years of daily readings. Through December, residents should expect elevated PM2.5 and PM10, reduced visibility on cooler mornings, and strong recommendations from doctors to limit outdoor exertion, wear well-fitted N95 masks, and run indoor purifiers through evening and overnight hours when pollutant accumulation typically peaks.
What is the cleanest month to visit Hosur?
August is the cleanest month of the year in Hosur, averaging AQI 55 in the Satisfactory band. The months immediately before and after also tend to sit well below the annual mean of 90, so a visit window centred on August is the safest choice for outdoor sightseeing, marathons, school trips and wedding events. Mornings are usually the crispest time to head out; pollution tends to creep up slightly during the evening commute even in the cleanest months. Always cross-check the day-of live AQI before any high-exertion outdoor plan.
Why does Hosur's air spike in December?
Hosur's profile is relatively flat year-round; the small December reflects modest swings in wind, rainfall and local emissions rather than a dramatic seasonal mechanism.
How bad is Diwali air quality in Hosur?
Across the CPCB record, the week around Diwali in Hosur averages AQI 124 — 1.52× the normal October baseline of AQI 82, a spike of 42 AQI points. Firework particulates combine with a cooler, more stagnant late-October atmosphere to produce some of the worst air-quality days of the entire year. Sensitive groups should treat Diwali eve and the two days after as peak-alert days: stay indoors, close windows by evening, run purifiers on high, and reserve any outdoor celebrations for daytime hours when mixing is strongest.
Does the monsoon actually clean Hosur's air?
Yes — meaningfully. Hosur's core monsoon window (Jul 15 – Sep 15) averages AQI 62, a 31.1% improvement on the annual mean of 90. Rain removes airborne particulates by wet deposition, and the deeper monsoon boundary layer disperses what remains vertically. Across 31 measured monsoon days we see 96.8% in the Good-or-Satisfactory band.
Is Hosur's worst season getting worse or better year-on-year?
We need more years of CPCB coverage in Hosur to quantify year-on-year change with confidence.
Which months are safest to visit Hosur?
August is the single best month at AQI 55. Based on the 12-month averages, the three cleanest months in Hosur are August (AQI 55), September (AQI 81), November (AQI 87). These are the safest choices for outdoor itineraries, long walks, open-air concerts and day-trips. Sensitive groups can treat these months as near-normal activity windows but should still check live AQI for the specific date. Avoid planning outdoor-heavy trips in December, when the baseline jumps into Moderate territory.
How does Hosur's seasonal pattern compare to Delhi?
Hosur is classified as flat year-round, while Delhi is strongly winter-dominant with a large Diwali and stubble-burning signal. If the two look similar, interventions that work in Delhi (BS-VI vehicle rollout, construction-dust control, seasonal industry curtailment) are worth trialling here. If they look very different, the dominant sources in Hosur are likely different and the policy mix should reflect that.