Ariyalur — Seasonal Pollution Patterns
Month-by-month air quality patterns for Ariyalur across 3 years of CPCB data. Based on CPCB station data, 2016–present.
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At a glance
Based on 3 years of CPCB monitoring across 1 stations, Ariyalur averages AQI 51 annually, with a pronounced seasonal pattern classified as flat year-round. The worst month is March at AQI 70 (Satisfactory) and the cleanest is September at AQI 33 (Good) — a 37-point swing between them. Severe days (AQI > 400) make up 0% of the record while Good-or-Satisfactory days account for 93.8%.
The four seasons
Indian meteorological seasons: Winter (Dec–Feb), Summer (Mar–May), Monsoon (Jun–Sep), Post-monsoon (Oct–Nov).
Winter
AQI 65Summer
AQI 60Monsoon
AQI 37Post-monsoon
AQI 42Climograph — 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 | — | — | — | — | — | — | — | — | — | — | — | 81 | 81 |
| 2023 | 85 | 87 | 73 | 55 | 50 | 47 | 34 | 82 | 32 | 46 | 37 | 45 | 55 |
| 2024 | 50 | 51 | 67 | 79 | 37 | 35 | 40 | 28 | 34 | 40 | 47 | 54 | 46 |
| Avg | 69 | 69 | 70 | 66 | 43 | 41 | 37 | 36 | 33 | 43 | 42 | 57 | — |
Winter in Ariyalur
Winter (Dec–Jan–Feb) in Ariyalur averages AQI 65 across 154 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 85.7% are Good or Satisfactory. Year-on-year, winter improved by 32.1% in the most recent comparison. Winter in Ariyalur is not the headline season, but shallow morning inversions can still produce short spikes. Ariyalur'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 62 (Satisfactory), versus 41 (Good) for the rest of October. 14 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 36 (Good), compared with an annual mean of 51.
Summer
Summer (Mar–Apr–May) in Ariyalur averages AQI 60 across 152 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 92.8% are Good or Satisfactory. Year-on-year, summer improved by 0.2% in the most recent comparison. Summer air in Ariyalur 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. Ariyalur's summer mean of 60 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 Ariyalur averages AQI 37 across 197 measured days — Good on the NAQI scale. 0% of those days fall in Very Poor or Severe; 98.5% are Good or Satisfactory. Year-on-year, monsoon improved by 15% in the most recent comparison. The Jul 15 – Sep 15 core monsoon window averages AQI 36, a 29.4% improvement on the annual mean of 51. 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 Ariyalur.
Post-monsoon
Post-monsoon (Oct–Nov) in Ariyalur averages AQI 42 across 107 measured days — Good on the NAQI scale. 0% of those days fall in Very Poor or Severe; 98.1% are Good or Satisfactory. Year-on-year, post-monsoon worsened by 5.2% in the most recent comparison. Diwali and the three days either side of it average AQI 62 — 1.51× the normal October baseline of AQI 41 for Ariyalur, a spike of 21 points. Post-monsoon in Ariyalur 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 3-year CPCB record.
First year vs latest year
Annual and per-season comparison.
Across the 3-year CPCB record Ariyalur is improving overall — AQI moved from 81 in 2022 to 46 in 2024, a -43.2% change. No month shows a material worsening of 10% or more. No month shows a material improvement of 10% or more. Because Ariyalur'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 3-year archive.
Month-by-month deep dive
Tap any month to expand.
Jan2023–2024Latest AQI 50-41%
Jan in Ariyalur averages AQI 50 (Good) in the most recent year, having moved from 85 in 2023. Direction: improving (-41.2%).
Feb2023–2024Latest AQI 51-41%
Feb in Ariyalur averages AQI 51 (Satisfactory) in the most recent year, having moved from 87 in 2023. Direction: improving (-41.4%).
Mar2023–2024Latest AQI 67-8%
Mar in Ariyalur averages AQI 67 (Satisfactory) in the most recent year, having moved from 73 in 2023. Direction: stable (-8.2%).
Apr2023–2024Latest AQI 79+44%
Apr in Ariyalur averages AQI 79 (Satisfactory) in the most recent year, having moved from 55 in 2023. Direction: worsening (+43.6%).
May2023–2024Latest AQI 37-26%
May in Ariyalur averages AQI 37 (Good) in the most recent year, having moved from 50 in 2023. Direction: improving (-26.0%).
Jun2023–2024Latest AQI 35-26%
Jun in Ariyalur averages AQI 35 (Good) in the most recent year, having moved from 47 in 2023. Direction: improving (-25.5%).
Jul2023–2024Latest AQI 40+18%
Jul in Ariyalur averages AQI 40 (Good) in the most recent year, having moved from 34 in 2023. Direction: worsening (+17.6%).
Aug2023–2024Latest AQI 28-66%
Aug in Ariyalur averages AQI 28 (Good) in the most recent year, having moved from 82 in 2023. Direction: improving (-65.9%).
Sep2023–2024Latest AQI 34+6%
Sep in Ariyalur averages AQI 34 (Good) in the most recent year, having moved from 32 in 2023. Direction: stable (+6.3%).
Oct2023–2024Latest AQI 40-13%
Oct in Ariyalur averages AQI 40 (Good) in the most recent year, having moved from 46 in 2023. Direction: improving (-13.0%).
Nov2023–2024Latest AQI 47+27%
Nov in Ariyalur averages AQI 47 (Good) in the most recent year, having moved from 37 in 2023. Direction: worsening (+27.0%).
Dec2022–2024Latest AQI 54-33%
Dec in Ariyalur averages AQI 54 (Satisfactory) in the most recent year, having moved from 81 in 2022. Direction: improving (-33.3%).
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 Ariyalur.
Opposite seasonal profile
Cities whose seasonal signature least resembles Ariyalur.
What to do with this information
If you are choosing when to visit Ariyalur 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 Ariyalur 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 Ariyalur?
March is the most polluted month in Ariyalur on average, with a long-run AQI of 70 — firmly in the Satisfactory band. This is drawn from 1 CPCB monitoring stations across 3 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 Ariyalur?
September is the cleanest month of the year in Ariyalur, averaging AQI 33 in the Good band. The months immediately before and after also tend to sit well below the annual mean of 51, 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 Ariyalur's air spike in March?
Ariyalur'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 Ariyalur?
Across the CPCB record, the week around Diwali in Ariyalur averages AQI 62 — 1.51× the normal October baseline of AQI 41, a spike of 21 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 Ariyalur's air?
Yes — meaningfully. Ariyalur's core monsoon window (Jul 15 – Sep 15) averages AQI 36, a 29.4% improvement on the annual mean of 51. Rain removes airborne particulates by wet deposition, and the deeper monsoon boundary layer disperses what remains vertically. Across 197 measured monsoon days we see 98.5% in the Good-or-Satisfactory band.
Is Ariyalur's worst season getting worse or better year-on-year?
Between 2022 and 2024, Ariyalur's annual average AQI moved from 81 to 46 — a change of -43.2%. In the most recent year-on-year comparison, the winter season specifically improved by 32.1%. The long-run direction is improving — NCAP policy pressure, cleaner fuels and tighter vehicle standards are showing up.
Which months are safest to visit Ariyalur?
September is the single best month at AQI 33. Based on the 12-month averages, the three cleanest months in Ariyalur are September (AQI 33), August (AQI 36), July (AQI 37). 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 Ariyalur's seasonal pattern compare to other Indian cities?
Ariyalur 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 Ariyalur's is Madikeri (Karnataka), 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 Ariyalur too. The peer-city panel on this page lists the closest four additional matches.