Imphal — Seasonal Pollution Patterns
Month-by-month air quality patterns for Imphal 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 2 stations, Imphal averages AQI 98 annually, with a pronounced seasonal pattern classified as flat year-round. The worst month is October at AQI 140 (Moderate) and the cleanest is July at AQI 74 (Satisfactory) — a 66-point swing between them. Severe days (AQI > 400) make up 1.1% of the record while Good-or-Satisfactory days account for 49.4%.
The four seasons
Indian meteorological seasons: Winter (Dec–Feb), Summer (Mar–May), Monsoon (Jun–Sep), Post-monsoon (Oct–Nov).
Winter
AQI 125Summer
AQI 96Monsoon
AQI 95Post-monsoon
AQI 152Climograph — 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 | — | — | — | 74 | 65 | 74 | 63 | 68 | 83 | 113 | 115 | 115 | 87 |
| 2024 | 113 | 102 | 102 | 100 | 99 | 99 | 100 | 101 | 125 | 187 | 103 | 103 | 110 |
| Avg | 113 | 102 | 102 | 92 | 83 | 86 | 75 | 79 | 96 | 140 | 113 | 111 | — |
Winter in Imphal
Winter (Dec–Jan–Feb) in Imphal averages AQI 125 across 112 measured days — Moderate on the NAQI scale. 1.8% of those days fall in Very Poor or Severe; 34.8% are Good or Satisfactory. Year-on-year, winter improved by 16.5% in the most recent comparison. Winter in Imphal is not the headline season, but shallow morning inversions can still produce short spikes. Imphal'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 137 (Moderate), versus 176 (Moderate) for the rest of October. 10 sampled days across the CPCB record.
Stubble-burning window (Oct 15 – Nov 15)
In-window severe-day share 0% vs 1.2% 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 92 (Satisfactory), compared with an annual mean of 111.
Summer
Summer (Mar–Apr–May) in Imphal averages AQI 96 across 124 measured days — Satisfactory on the NAQI scale. 0% of those days fall in Very Poor or Severe; 71.8% are Good or Satisfactory. Year-on-year, summer worsened by 40.6% in the most recent comparison. Summer air in Imphal 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. Imphal's summer mean of 96 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 Imphal averages AQI 95 across 218 measured days — Satisfactory on the NAQI scale. 0.9% of those days fall in Very Poor or Severe; 59.2% are Good or Satisfactory. Year-on-year, monsoon worsened by 26.1% in the most recent comparison. The Jul 15 – Sep 15 core monsoon window averages AQI 92, a 17.1% improvement on the annual mean of 111. 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 Imphal.
Post-monsoon
Post-monsoon (Oct–Nov) in Imphal averages AQI 152 across 97 measured days — Moderate on the NAQI scale. 7.2% of those days fall in Very Poor or Severe; 15.5% are Good or Satisfactory. Year-on-year, post-monsoon worsened by 20.2% in the most recent comparison. Post-monsoon in Imphal 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 Imphal is worsening overall — AQI moved from 87 in 2022 to 110 in 2024, a +26.4% change. No month shows a material worsening of 10% or more. No month shows a material improvement of 10% or more. Because Imphal's seasonal shape is flat year-round, policy action that targets the October 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.
Jan2024–2024Latest AQI 113+0%
Jan in Imphal averages AQI 113 (Moderate) in the most recent year, having moved from 113 in 2024. Direction: stable (+0.0%).
Feb2024–2024Latest AQI 102+0%
Feb in Imphal averages AQI 102 (Moderate) in the most recent year, having moved from 102 in 2024. Direction: stable (+0.0%).
Mar2024–2024Latest AQI 102+0%
Mar in Imphal averages AQI 102 (Moderate) in the most recent year, having moved from 102 in 2024. Direction: stable (+0.0%).
Apr2022–2024Latest AQI 100+35%
Apr in Imphal averages AQI 100 (Satisfactory) in the most recent year, having moved from 74 in 2022. Direction: worsening (+35.1%).
May2022–2024Latest AQI 99+52%
May in Imphal averages AQI 99 (Satisfactory) in the most recent year, having moved from 65 in 2022. Direction: worsening (+52.3%).
Jun2022–2024Latest AQI 99+34%
Jun in Imphal averages AQI 99 (Satisfactory) in the most recent year, having moved from 74 in 2022. Direction: worsening (+33.8%).
Jul2022–2024Latest AQI 100+59%
Jul in Imphal averages AQI 100 (Satisfactory) in the most recent year, having moved from 63 in 2022. Direction: worsening (+58.7%).
Aug2022–2024Latest AQI 101+49%
Aug in Imphal averages AQI 101 (Moderate) in the most recent year, having moved from 68 in 2022. Direction: worsening (+48.5%).
Sep2022–2024Latest AQI 125+51%
Sep in Imphal averages AQI 125 (Moderate) in the most recent year, having moved from 83 in 2022. Direction: worsening (+50.6%).
Oct2022–2024Latest AQI 187+66%
Oct in Imphal averages AQI 187 (Moderate) in the most recent year, having moved from 113 in 2022. Direction: worsening (+65.5%).
Nov2022–2024Latest AQI 103-10%
Nov in Imphal averages AQI 103 (Moderate) in the most recent year, having moved from 115 in 2022. Direction: improving (-10.4%).
Dec2022–2024Latest AQI 103-10%
Dec in Imphal averages AQI 103 (Moderate) in the most recent year, having moved from 115 in 2022. Direction: improving (-10.4%).
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 Imphal.
Opposite seasonal profile
Cities whose seasonal signature least resembles Imphal.
What to do with this information
If you are choosing when to visit Imphal or plan outdoor events — marathons, weddings, school sports, outdoor festivals — the CPCB record says July 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 October in Imphal 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 Imphal?
October is the most polluted month in Imphal on average, with a long-run AQI of 140 — firmly in the Moderate band. This is drawn from 2 CPCB monitoring stations across 3 years of daily readings. Through October, 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 Imphal?
July is the cleanest month of the year in Imphal, averaging AQI 74 in the Satisfactory band. The months immediately before and after also tend to sit well below the annual mean of 98, so a visit window centred on July 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 Imphal's air spike in October?
Imphal's profile is relatively flat year-round; the small October reflects modest swings in wind, rainfall and local emissions rather than a dramatic seasonal mechanism.
How bad is Diwali air quality in Imphal?
Across the CPCB record, the week around Diwali in Imphal averages AQI 137 — 0.78× the normal October baseline of AQI 176, a shift of 39 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 Imphal's air?
Only partially. Imphal's monsoon window averages AQI 92, which is a 17.1% change from the annual mean of 111. Rain does scrub particulates, but the improvement here is modest — pointing to persistent local sources (industry, traffic, dust) that rain cannot fully wash away.
Is Imphal's worst season getting worse or better year-on-year?
Between 2022 and 2024, Imphal's annual average AQI moved from 87 to 110 — a change of +26.4%. In the most recent year-on-year comparison, the winter season specifically improved by 16.5%. The long-run direction is worsening — rapid urbanisation and emissions growth appear to be outpacing efficiency gains.
Which months are safest to visit Imphal?
July is the single best month at AQI 74. Based on the 12-month averages, the three cleanest months in Imphal are July (AQI 74), August (AQI 79), May (AQI 83). 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 October, when the baseline jumps into Moderate territory.
How does Imphal's seasonal pattern compare to other Indian cities?
Imphal 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 Imphal's is Bāgalkot (Karnataka), with its own worst month in January. 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 Imphal too. The peer-city panel on this page lists the closest four additional matches.