Fine particles
3.7µg/m³Good · 1 hourCAMS model • Open-Meteo
San JoséAir quality, PM2.5 and PM10
Check PM2.5 and PM10 particle levels alongside ozone, nitrogen dioxide and other gases. Compare the latest available concentrations with recent days and explore changes in air pollution through the available historical records.
San José - latest available concentrations (September 26, 2026, 19:00 local time): PM2.5: 3.7 µg/m³, PM10: 3.7 µg/m³, O₃: 12 µg/m³, NO₂: 29.8 µg/m³, SO₂: 5.4 µg/m³, CO: 837 µg/m³. These are hourly CAMS model values for a point representing the city.
Air quality questions →San José · Air pollutant concentrations
Data time: September 26, 2026 · 19:00 · local timeParticulate matter
3.7µg/m³Good · 1 hourOzone
12µg/m³Good · 1 hourNitrogen dioxide
29.8µg/m³Moderate · 1 hourSulphur dioxide
5.4µg/m³Good · 1 hourCarbon monoxide
837µg/m³PM2.5 vs PM10 - what is the difference? → · Models and monitoring stations →
DAILY DATA · San José
San José - air pollution over recent days (2026-08-30 - 2026-09-25)
Concentrations of all available pollutants for this city.
PM2.5Lowest 3.98 2026-08-30Highest 12.82 2026-09-222026-08-30 - 2026-09-25
PM10Lowest 4.51 2026-08-30Highest 12.91 2026-09-222026-08-30 - 2026-09-25
O₃Lowest 28.58 2026-09-01Highest 47.88 2026-09-052026-08-30 - 2026-09-25
NO₂Lowest 6.15 2026-09-05Highest 24.99 2026-09-222026-08-30 - 2026-09-25
SO₂Lowest 2.78 2026-08-30Highest 5.13 2026-09-232026-08-30 - 2026-09-25
COLowest 193.38 2026-08-30Highest 767.58 2026-09-252026-08-30 - 2026-09-25
Scroll the chart or table sideways to see the full period.
| Pollutant | 2026-09-25 | 2026-09-24 | 2026-09-23 | 2026-09-22 | 2026-09-21 | 2026-09-20 | 2026-09-19 | 2026-09-06 | 2026-09-05 | 2026-09-04 | 2026-09-03 | 2026-09-02 | 2026-09-01 | 2026-08-31 | 2026-08-30 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 | 7.86 | 7.69 | 12.08 | 12.82 | 6.46 | 5.48 | 6.76 | 5.34 | 4.22 | 7.54 | 7.31 | 10.26 | 7.96 | 7.1 | 3.98 |
| PM10 | 8.07 | 8 | 12.19 | 12.91 | 6.59 | 5.67 | 7.85 | 6.03 | 4.9 | 8.87 | 8.5 | 11.26 | 9.61 | 8.4 | 4.51 |
| O₃ | 42.25 | 42.13 | 39.42 | 37.96 | 36.08 | 35.29 | 32.42 | 35.75 | 47.88 | 34.75 | 31.29 | 29.04 | 28.58 | 31.54 | 32.96 |
| NO₂ | 15.35 | 14.55 | 21.17 | 24.99 | 19.1 | 13.12 | 12.08 | 8.88 | 6.15 | 10.72 | 12.45 | 17.35 | 14.57 | 10.83 | 6.69 |
| SO₂ | 4.9 | 4.62 | 5.13 | 4.63 | 4.82 | 4.53 | 4.6 | 3.2 | 2.91 | 3.25 | 3.68 | 4.13 | 3.67 | 3.39 | 2.78 |
| CO | 767.58 | 700 | 748.08 | 681.17 | 498.17 | 430.79 | 369.13 | 373.13 | 195.71 | 304.5 | 295.21 | 405.83 | 476.38 | 279.63 | 193.38 |
A dot on the chart and a dash in the table indicate missing data. The latest day may be incomplete.
Environment and quality of life ratings · San José
Archived ratings of the local environment: green spaces, cleanliness, noise and water quality. Opinion indicators are separate from pollutant concentration measurements.
| Indicator | San José | Nicaragua | Panama | Honduras | El Salvador | Guatemala |
|---|---|---|---|---|---|---|
| Green and Parks in the City | 59% | 43% | 51% | 41% | 37% | 45% |
| particulate matter PM2.5 (µg/m³) | 24 | — | — | — | — | — |
| Pleasure of spending time in the city | 51% | 52% | 55% | 41% | 40% | 45% |
| particulate matter PM10 (µg/m³) | 27 | — | — | — | — | — |
| Air Pollution | 42% | 39% | 42% | 65% | 65% | 64% |
| Garbage Disposal | 38% | 30% | 33% | 22% | 33% | 30% |
| Availability and quality of drinking water | 78% | 49% | 66% | 44% | 41% | 39% |
| Cleanliness and tidiness | 32% | 29% | 37% | 20% | 29% | 34% |
| Noise and Light pollution | 54% | 63% | 60% | 49% | 57% | 56% |
| Water Pollution | 49% | 73% | 57% | 72% | 68% | 71% |
Air quality in nearby cities
All cities →Costa Rica · air quality in other cities
WEATHER & SURROUNDINGS
Costa Rica · weather forecast
Daily maximum and minimum temperatures. Forecast point: 9.7489, -83.7534. Forecast for a country reference point; conditions in the city may differ.
Scroll the forecast to see the following days.
Costa Rica · September 24, 2026: minimum temperature 15.3°C, maximum 23.3°C. Wind: 9.3 km/h. Humidity: 68%.
Full forecast: temperature, rainfall, wind and humidity
| Date | Day °C | Min °C | Max °C | Night °C | Rain mm | Wind m/s | Humidity % | Clouds % |
|---|---|---|---|---|---|---|---|---|
| 2026-09-24 | 23.3 | 15.3 | 23.3 | 17.4 | 11 | 2.6 | 68 | 35 |
| 2026-09-25 | 21.6 | 15.7 | 21.6 | 17.4 | 24.3 | 1.6 | 72 | 98 |
| 2026-09-26 | 22.2 | 15.8 | 23.2 | 17.1 | 6.8 | 1.7 | 58 | 84 |
| 2026-09-27 | 23 | 15.9 | 23.8 | 17.8 | 1.8 | 2.1 | 60 | 96 |
| 2026-09-28 | 24.8 | 16.4 | 24.8 | 17.8 | 3.8 | 2.7 | 60 | 89 |
| 2026-09-29 | 25 | 16.5 | 25 | 17.5 | 0.8 | 2.3 | 59 | 70 |
| 2026-09-30 | 23.9 | 15.9 | 23.9 | 18 | 7 | 1.7 | 62 | 96 |
| 2026-10-01 | 21.2 | 16.4 | 22.9 | 18.1 | 18.6 | 1.1 | 87 | 99 |
| 2026-10-02 | 22.1 | 16.9 | 22.2 | 17.9 | 24.9 | 1.3 | 87 | 99 |
| 2026-10-03 | 23.6 | 16.3 | 23.6 | 17.3 | 10 | 2.3 | 73 | 96 |
| 2026-10-04 | 24.4 | 15.9 | 24.4 | 17.2 | 5.2 | 2.2 | 67 | 100 |
| 2026-10-05 | 21.5 | 16 | 22 | 17 | 34.5 | 1.2 | 80 | 100 |
| 2026-10-06 | 20.1 | 16.3 | 21.7 | 16.5 | 17.5 | 2.2 | 89 | 100 |
| 2026-10-07 | 19.5 | 16.1 | 19.5 | 16.6 | 4.9 | 2 | 91 | 100 |
| 2026-10-08 | 20.8 | 16.5 | 21.6 | 16.7 | 8.7 | 2.2 | 83 | 100 |
| 2026-10-09 | 19 | 15.8 | 22.5 | 17.3 | 10.4 | 1.7 | 95 | 98 |
| 2026-10-10 | 22.1 | 16.8 | 22.2 | 17.4 | 8.6 | 1.9 | 82 | 99 |
UV index by day · Costa Rica
Data for a country reference point. Local conditions may differ.
SPF 50, long sleeves and shade between 10:00-16:00.
0-2 low3-5 moderate6-7 high8-10 very high11+ extreme
Scroll the forecast to see the following days.
Costa Rica · September 26, 2026: UV index: 8.1 .
| Indicator | 2026-09-26 | 2026-09-27 | 2026-09-28 | 2026-09-29 | 2026-09-30 | 2026-10-01 | 2026-10-02 | 2026-10-03 | 2026-10-04 | 2026-10-05 | 2026-10-06 | 2026-10-07 | 2026-10-08 | 2026-10-09 | 2026-10-10 | 2026-10-11 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index | 8.1 | 8.8 | 9.1 | 5.7 | 8.1 | 6.9 | 7.6 | 9 | 8.7 | 7.1 | 7 | 6.7 | 7.2 | 5.7 | 7.2 | — |
AIR QUALITY QUESTIONS
San José · air pollution - questions and answers
What do the latest air quality data show for San José?
San José - latest available concentrations (September 26, 2026, 19:00 local time): PM2.5: 3.7 µg/m³, PM10: 3.7 µg/m³, O₃: 12 µg/m³, NO₂: 29.8 µg/m³, SO₂: 5.4 µg/m³, CO: 837 µg/m³. These are hourly CAMS model values for a point representing the city.
When was PM2.5 highest in San José over the past week?
The highest available daily mean PM2.5 was 12.8 µg/m³ (September 22, 2026). This comparison covers 7 days with data in the seven days before September 26, 2026. The day of the latest reading is excluded because it may be incomplete.
Is the PM2.5 concentration for San José an AQI score?
No. PM2.5 and PM10 are concentrations in µg/m³. AQI is a separate index calculated using a defined scale. When comparing air quality, also check other pollutants, the date and the averaging period.
What UV index does the available forecast show for San José?
For September 26, 2026, the forecast UV index is 8.1. The UV section also shows the following available days. The forecast is for a country reference point (Costa Rica), not the city itself.
What wind speed is forecast for San José?
For September 24, 2026, forecast wind speed is 9.3 km/h. The weather table includes wind, temperature and other available parameters for subsequent days. These data describe a country reference point (Costa Rica); local wind may differ.
PM2.5 · PM10 · NO₂ · O₃
Understanding air quality and pollution data
What do PM2.5 and PM10 mean?
PM2.5 and PM10 are fractions of airborne particulate matter. PM2.5 covers fine particles up to 2.5 micrometres in diameter, while PM10 covers particles up to 10 micrometres. Concentrations in µg/m³ tell you how many micrograms of particles are present in a cubic metre of air. Compare values over the same time period.
Where does the air pollution data come from?
The latest concentrations come from the CAMS atmospheric model via Open-Meteo for each city’s coordinates. Values describe a model area, so conditions on individual streets may differ. Historical monitoring station data is shown separately where available.
How does PM2.5 concentration differ from AQI?
PM2.5 is the concentration of one particle fraction, expressed in µg/m³. AQI is an index calculated using a particular scale and thresholds. The pollutant cards show concentrations. Our city ranking compares PM2.5; PM10, ozone, nitrogen dioxide and other available gases add to the picture of air quality.
Which dates do the values and charts cover?
Each current value has a data date and time. Current concentration cards show the latest available hour, daily charts summarise individual days, and monthly records let you compare longer periods. These values represent different time intervals.
How can I check pollution in my city?
Search for your city and open its air quality page. Start with PM2.5 and PM10, then check the other available pollutants and the data timestamp. Charts and tables help you compare concentrations over time. Weather and historical climate information complement the pollution data.