Weather forecast for the selected location.
Next 2 hours from CHMI radar
A detailed hourly forecast is available only for the next 48 hours.
Default location: Vysočany
Valid air quality, pollen and UV data for Vysočany are unavailable.
Missing data do not mean a low health burden or a UV index of zero.
Air quality and the UV index for the selected location.
European air quality index, modelled pollen concentrations and UV index for the selected location. The source and time beside each value show what it describes.
EAQI is dimensionless, rather than a concentration. The highest sub-index among PM2.5, PM10, O3, NO2 and SO2 determines the result; sub-indices are comparable, but raw concentrations of different pollutants are not.
PM2.5 and PM10 denote particle size fractions, O3 ground-level ozone, NO2 nitrogen dioxide and SO2 sulphur dioxide. Concentrations use µg/m³, micrograms per cubic metre of air. For O3, NO2 and SO2, the number shown here is a sub-index; PM2.5 and PM10 show concentrations.
WHO provides health guidelines, while the EU sets legal limits and an ozone target value. A single hourly value cannot establish an exceedance of an annual or daily limit. These tables do not assess the live values shown above.
| Pollutant | Average | Value |
|---|---|---|
| PM2.5 | year | 5 |
| PM2.5 | 24 h | 15 |
| PM10 | year | 15 |
| PM10 | 24 h | 45 |
| O3 | peak season | 60 |
| O3 | 8 h | 100 |
| NO2 | year | 10 |
| NO2 | 24 h | 25 |
| SO2 | 24 h | 40 |
WHO short-term guidelines refer to the 99th percentile of daily values. The ozone peak-season value averages daily maximum eight-hour means over the six consecutive months with the highest concentrations.
| Pollutant | Average | 2008/50/EC | 2024/2881 for 2030 | Permitted exceedances per year, earlier / 2030 |
|---|---|---|---|---|
| PM2.5 | year | 25 | 10 | no permitted exceedances |
| PM2.5 | 24 h | not set | 25 | — / 18 days |
| PM10 | year | 40 | 20 | no permitted exceedances |
| PM10 | 24 h | 50 | 45 | 35 / 18 days |
| NO2 | year | 40 | 20 | no permitted exceedances |
| NO2 | 1 h | 200 | 200 | 18 / 3 hours |
| NO2 | 24 h | not set | 50 | — / 18 days |
| SO2 | year | not set | 20 | — / no exceedances |
| SO2 | 1 h | 350 | 350 | 24 / 3 hours |
| SO2 | 24 h | 125 | 50 | 3 / 18 days |
| O3 | daily maximum 8 h | 120 | 120 | 25 / 18 days |
The tighter EU values have a 1 January 2030 attainment deadline; they are not today’s limits. O3 has a target value with permitted days averaged over three years. The table omits other legal conditions and possible deadline extensions.
A station samples air at one location, while a model represents a grid area. Nearby traffic or a local source can therefore affect a station differently from a model. Compare the same pollutant, location, time and averaging period.
CAMS combines models with observations, but its forecast is not a local measurement. The Czech Hydrometeorological Institute also uses its own index methodology with three-hour rolling means, so its categories are not equivalent to EAQI here. Missing data do not mean zero concentration.
Pollen concentration is the number of grains per cubic metre of air, grains/m³. The pollen card shows a modelled daily mean, which may miss a brief local peak. A pollen band is not the probability of your symptoms.
| Season | Typical pollen |
|---|---|
| spring | alder, hazel, then birch |
| late spring and summer | grasses |
| summer and early autumn | mugwort and ragweed |
Season timing depends on weather and local vegetation, rather than a fixed calendar for every town. Airflow can also bring pollen from another region. CAMS checks pollen forecasts against EAN station observations; its pollen variables have experimental status.
UV index uses radiation weighted by its ability to cause skin redness, or erythema. Erythemally effective irradiance Eery is in W/m²; the index is dimensionless. Dose in J/m² accumulates irradiance over time and cannot be determined from the index alone.
UVI = Eery / (0.025 W/m²) = 40 m²/W × Eery
| UV index | Category |
|---|---|
| 0–2 | low |
| 3–5 | moderate |
| 6–7 | high |
| 8–10 | very high |
| 11+ | extreme |
Use the card label to distinguish a current index from the daily maximum. WHO recommends protection from UV index 3, including shade, clothing, a hat, sunglasses and sunscreen. We do not infer a personal safe exposure time from the index.
CHMI warnings for the selected location.
CHMI