Hassan — Seasonal Pollution Patterns
Month-by-month air quality patterns for Hassan across 4 years of CPCB data. Based on CPCB station data, 2016–present.
Karnataka · Live Hassan AQI →
At a glance
Based on 4 years of CPCB monitoring across 1 stations, Hassan averages AQI 63 annually, with a pronounced seasonal pattern classified as flat year-round. The worst month is March at AQI 89 (Satisfactory) and the cleanest is September at AQI 41 (Good) — a 48-point swing between them. Severe days (AQI > 400) make up 0% of the record while Good-or-Satisfactory days account for 92.5%.
The four seasons
Indian meteorological seasons: Winter (Dec–Feb), Summer (Mar–May), Monsoon (Jun–Sep), Post-monsoon (Oct–Nov).
Winter
AQI 73Summer
AQI 82Monsoon
AQI 47Post-monsoon
AQI 57Climograph — 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2021 | — | — | 141 | 100 | 57 | 65 | 48 | 62 | 52 | 46 | 48 | 76 | 64 |
| 2022 | 72 | 86 | 90 | 81 | 76 | 45 | 40 | 47 | 29 | 42 | 61 | 59 | 61 |
| 2023 | 74 | 82 | 87 | 78 | 62 | 52 | 47 | 48 | 50 | 84 | 62 | 70 | 69 |
| 2024 | 81 | 67 | 76 | 77 | 89 | 55 | 49 | 32 | 38 | 54 | 65 | 67 | 60 |
| Avg | 75 | 79 | 89 | 86 | 70 | 56 | 45 | 48 | 41 | 54 | 59 | 67 | — |
Winter in Hassan
Winter (Dec–Jan–Feb) in Hassan averages AQI 73 across 226 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 92% are Good or Satisfactory. Year-on-year, winter improved by 6.8% in the most recent comparison. Winter in Hassan is not the headline season, but shallow morning inversions can still produce short spikes. Hassan'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 52 (Satisfactory), versus 54 (Satisfactory) for the rest of October. 24 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 46 (Good), compared with an annual mean of 63.
Summer
Summer (Mar–Apr–May) in Hassan averages AQI 82 across 262 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 80.9% are Good or Satisfactory. Year-on-year, summer worsened by 2.3% in the most recent comparison. Summer air in Hassan 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. Hassan's summer mean of 82 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 Hassan averages AQI 47 across 354 measured days — Good on the NAQI scale. 0% of those days fall in Very Poor or Severe; 98.6% are Good or Satisfactory. Year-on-year, monsoon improved by 15.3% in the most recent comparison. The Jul 15 – Sep 15 core monsoon window averages AQI 46, a 27% improvement on the annual mean of 63. 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 Hassan.
Post-monsoon
Post-monsoon (Oct–Nov) in Hassan averages AQI 57 across 186 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 97.8% are Good or Satisfactory. Year-on-year, post-monsoon improved by 18.1% in the most recent comparison. Post-monsoon in Hassan 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 4-year CPCB record.
First year vs latest year
Annual and per-season comparison.
Across the 4-year CPCB record Hassan is roughly stable overall — AQI moved from 64 in 2021 to 60 in 2024, a -6.2% change. Months that worsened most: May (+56.1%), Oct (+17.4%), Nov (+35.4%). Months that improved most: Mar (-46.1%), Apr (-23%), Jun (-15.4%), Aug (-48.4%). Because Hassan's seasonal shape is flat year-round, policy action that targets the March peak buys disproportionate relief — most city-wide annual averages are dragged upwards by the worst two or three months.
Daily calendar heatmap
Every measured day for the last 3 years. Expand for the full 4-year archive.
Month-by-month deep dive
Tap any month to expand.
Jan2022–2024Latest AQI 81+13%
Jan in Hassan averages AQI 81 (Satisfactory) in the most recent year, having moved from 72 in 2022. Direction: worsening (+12.5%).
Feb2022–2024Latest AQI 67-22%
Feb in Hassan averages AQI 67 (Satisfactory) in the most recent year, having moved from 86 in 2022. Direction: improving (-22.1%).
Mar2021–2024Latest AQI 76-46%
Mar in Hassan averages AQI 76 (Satisfactory) in the most recent year, having moved from 141 in 2021. Direction: improving (-46.1%).
Apr2021–2024Latest AQI 77-23%
Apr in Hassan averages AQI 77 (Satisfactory) in the most recent year, having moved from 100 in 2021. Direction: improving (-23.0%).
May2021–2024Latest AQI 89+56%
May in Hassan averages AQI 89 (Satisfactory) in the most recent year, having moved from 57 in 2021. Direction: worsening (+56.1%).
Jun2021–2024Latest AQI 55-15%
Jun in Hassan averages AQI 55 (Satisfactory) in the most recent year, having moved from 65 in 2021. Direction: improving (-15.4%).
Jul2021–2024Latest AQI 49+2%
Jul in Hassan averages AQI 49 (Good) in the most recent year, having moved from 48 in 2021. Direction: stable (+2.1%).
Aug2021–2024Latest AQI 32-48%
Aug in Hassan averages AQI 32 (Good) in the most recent year, having moved from 62 in 2021. Direction: improving (-48.4%).
Sep2021–2024Latest AQI 38-27%
Sep in Hassan averages AQI 38 (Good) in the most recent year, having moved from 52 in 2021. Direction: improving (-26.9%).
Oct2021–2024Latest AQI 54+17%
Oct in Hassan averages AQI 54 (Satisfactory) in the most recent year, having moved from 46 in 2021. Direction: worsening (+17.4%).
Nov2021–2024Latest AQI 65+35%
Nov in Hassan averages AQI 65 (Satisfactory) in the most recent year, having moved from 48 in 2021. Direction: worsening (+35.4%).
Dec2021–2024Latest AQI 67-12%
Dec in Hassan averages AQI 67 (Satisfactory) in the most recent year, having moved from 76 in 2021. Direction: improving (-11.8%).
Cities with similar (and opposite) seasonal profiles
Ranked by cosine similarity of 12-month AQI signatures across monitored Indian cities.
Similar seasonal profile
Cities whose 12-month AQI signature most closely matches Hassan.
Opposite seasonal profile
Cities whose seasonal signature least resembles Hassan.
What to do with this information
If you are choosing when to visit Hassan or plan outdoor events — marathons, weddings, school sports, outdoor festivals — the CPCB record says September 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 March in Hassan 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 Hassan?
March is the most polluted month in Hassan on average, with a long-run AQI of 89 — firmly in the Satisfactory band. This is drawn from 1 CPCB monitoring stations across 4 years of daily readings. Through March, 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 Hassan?
September is the cleanest month of the year in Hassan, averaging AQI 41 in the Good band. The months immediately before and after also tend to sit well below the annual mean of 63, so a visit window centred on September 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 Hassan's air spike in March?
Hassan's profile is relatively flat year-round; the small March reflects modest swings in wind, rainfall and local emissions rather than a dramatic seasonal mechanism.
How bad is Diwali air quality in Hassan?
Across the CPCB record, the week around Diwali in Hassan averages AQI 52 — 0.97× the normal October baseline of AQI 54, a shift of 2 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 Hassan's air?
Yes — meaningfully. Hassan's core monsoon window (Jul 15 – Sep 15) averages AQI 46, a 27% improvement on the annual mean of 63. Rain removes airborne particulates by wet deposition, and the deeper monsoon boundary layer disperses what remains vertically. Across 354 measured monsoon days we see 98.6% in the Good-or-Satisfactory band.
Is Hassan's worst season getting worse or better year-on-year?
Between 2021 and 2024, Hassan's annual average AQI moved from 64 to 60 — a change of -6.2%. In the most recent year-on-year comparison, the winter season specifically improved by 6.8%. The long-run direction is roughly stable — underlying growth in emissions is being offset by cleaner technology or weather variability.
Which months are safest to visit Hassan?
September is the single best month at AQI 41. Based on the 12-month averages, the three cleanest months in Hassan are September (AQI 41), July (AQI 45), August (AQI 48). 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 March, when the baseline jumps into Satisfactory territory.
How does Hassan's seasonal pattern compare to other Indian cities?
Hassan is classified as flat year-round. Based on a 12-month cosine-similarity index computed across all monitored Indian cities, the city whose seasonal signature most closely resembles Hassan's is Kannur (Kerala), with its own worst month in February. Cities with similar signatures often respond to similar policy levers — if a neighbouring peer has demonstrated improvements through specific interventions (construction-dust controls, bus electrification, brick-kiln regulation), they are likely candidates for Hassan too. The peer-city panel on this page lists the closest four additional matches.