Forecast details

Air temperature

Shows the temperature in the shade at a height of 2 m above the Earth's surface.

Calculations take into account the data received from weather stations which have special conditions for measuring air temperature:
  • Located at a height of 2 m from the ground.
  • Open to the wind.
  • Not affected by direct sunlight.

Household thermometers are not always installed according to the same rules, therefore their readings may differ from the temperature on Yandex.Weather.

Daylight hours

The time from sunrise to sunset.

Yandex.Weather calculates daylight hours considering atmospheric refraction, a phenomenon associated with light deflection and scattering. When light passes from the more dense layers of the atmosphere to the less dense ones (and vice versa), its speed changes and the sun rays deviate from a straight line. Atmospheric refraction is especially noticeable when the sun is near the horizon: when it is already below the horizon, you can still see the sun's disk.

Daylight duration increases due to atmospheric refraction.

You can see the sunrise and sunset time on the Yandex.Weather homepage and in the detailed forecast. The detailed forecast shows daylight hours.

Feels like

The same temperature values can be perceived differently, depending on humidity, wind force, and other factors. For example, a temperature of –5° feels a lot colder when there's a strong wind, and a warm day feels hot if the humidity is high. This is why the forecast displays a Feels like indicator. It shows how comfortable the weather conditions are.

When calculating the “feels like” temperature, the following is taken into account:

  • Air temperature.
  • Humidity.
  • Wind speed.
  • Solar radiation.
Note. The “feels like” temperature is calculated as an average for most people. Each person's warmth sense is individual, so it may differ from the Feels like indicator.

Humidity

Shows the amount of water vapor in the air. Humidity is measured 2 m above ground.

High humidity increases the likelihood of dew or fog.

Humidity is affected by processes that depend on terrain features:
  • Moisture transfer by air flows.
  • Water evaporation.

The forecast shows the relative humidity of the air, i.e. the amount of water vapor in the air as compared with the maximum amount of water that the air could possibly hold at the current temperature.

Humidity is displayed in the weather card on the Yandex.Weather homepage and in the detailed forecast.

Magnetic field

The magnetic field is affected by solar activity. When solar flares occur, a stream of particles reaches the Earth and impacts its magnetic field.

Researchers measure the state of the magnetic field with the Kp index. It shows the average deviation of the entire Earth's magnetic field from the norm calculated for three-hour intervals. The Kp index values range from 1 (quiet activity) to 10 (extreme magnetic storm).

In the service, the values of the Kp index correspond to the following verbal definitions:

Kp index State of magnetic field in Yandex.Weather

Less than 4

Quiet

4

Unstable

5

Slightly disturbed

6

Disturbed

7

Magnetic storm

8 or higher

Strong magnetic storm

Kp index State of magnetic field in Yandex.Weather

Less than 4

Quiet

4

Unstable

5

Slightly disturbed

6

Disturbed

7

Magnetic storm

8 or higher

Strong magnetic storm

You can see the state of the magnetic field in the detailed forecast. Yandex.Weather shows the current state of the magnetic field for today and the next three days. No forecast is made for subsequent days, as its accuracy is low.

Magnetic field disturbances may cause a communication blackout and power system failures. Some people may be affected by the force of a magnetic storm.

Moon phase

Shows how much the moon is illuminated by the sun.

On the Yandex.Weather homepage, in the forecast for today, you can see textual information about the phase of the moon.

In the detailed 10-day forecast, the phase of the moon is displayed as an image. The yellow portion of the disk shows the visible part of the moon, while the dark-gray one reflects its invisible part.

Icon Moon phase Approximate time when the moon is visible in the sky

New moon

Not visible

Waxing crescent

09:00–21:00

First quarter

12:00–00:00

Waxing gibbous

15:00–03:00

Full moon

18:00–06:00

Waning gibbous

21:00–09:00

Last quarter

00:00–12:00

Waning crescent

03:00–15:00

Icon Moon phase Approximate time when the moon is visible in the sky

New moon

Not visible

Waxing crescent

09:00–21:00

First quarter

12:00–00:00

Waxing gibbous

15:00–03:00

Full moon

18:00–06:00

Waning gibbous

21:00–09:00

Last quarter

00:00–12:00

Waning crescent

03:00–15:00

Pressure

Pressure is affected by atmospheric circulation.

When a cyclone is coming, the atmospheric pressure decreases, and when an anticyclone is coming, the pressure increases.

To determine the type of atmospheric circulation, open the Wind tab on the weather maps and see in which direction the air flow is moving over your city:
  • If the air is moving counterclockwise, it's a cyclone.
  • If the air is moving clockwise, it's an anticyclone.
Note. In the Southern hemisphere, the cyclone rotates clockwise and the anticyclone — counterclockwise.

Most people are accustomed to the pressure of 760 millimeters of mercury. But the normal atmospheric pressure for each person depends on the region they live in, while the pressure of the region depends on the terrain altitude. For example, in Vienna the average altitude is 151 m and the standard pressure for it is 744 mmHg. Therefore, the pressure of 760 mmHg for the residents of Vienna is not normal, but elevated.

Difference from the norm for the region, mmHg Pressure value
More than 20 below the norm for the region Low
10-20 lower than the norm for the region Reduced
Within 10 above the norm for the region Standard
10-20 higher than the norm for the region Increased
More than 20 above the norm for the region High
Difference from the norm for the region, mmHg Pressure value
More than 20 below the norm for the region Low
10-20 lower than the norm for the region Reduced
Within 10 above the norm for the region Standard
10-20 higher than the norm for the region Increased
More than 20 above the norm for the region High

UV index

Describes the level of solar radiation at the surface of the Earth and whether it's dangerous to humans.

The index value depends on the following parameters:
  • Seasonal activity of the sun.
  • The sun's position relative to the latitude, horizon, and sea level.
  • The condition of the ozone layer above the area.
  • Aerosol concentration in the air.
  • Terrain reflectivity.
  • Type of clouds.
Note. Most often, in cloudy and rainy weather, the UV index is low, while in a fog, the solar radiation is repeatedly reflected and dispersed, and the UV index increases. This effect is often visible in the mountains.
How to protect yourself from solar radiation
UV index value WHO recommendations

0-2: low

There is minimal risk of sunburn, even if your skin is sensitive.
3-7: moderate Try to stay in the shade from 12:00 to 16:00.

Use sunscreen with SPF 15-30.

Wear a hat and a long-sleeve shirt.

More than 8: very high

Avoid being outside from 12:00 to 16:00.

Use 50 SPF sunscreen.

Wear protective clothing and sunglasses.

UV index value WHO recommendations

0-2: low

There is minimal risk of sunburn, even if your skin is sensitive.
3-7: moderate Try to stay in the shade from 12:00 to 16:00.

Use sunscreen with SPF 15-30.

Wear a hat and a long-sleeve shirt.

More than 8: very high

Avoid being outside from 12:00 to 16:00.

Use 50 SPF sunscreen.

Wear protective clothing and sunglasses.

Where to find the UV index

The current UV index value is displayed on the Yandex.Weather homepage.

You can find out the UV index value for the next four days in the detailed forecast.

Water temperature

Shows water surface temperature.

Water temperature is only displayed for cities located near large water bodies. If the weather stations nearest to the city do not measure water temperature, Yandex.Weather calculates this indicator itself.

You can see the water temperature on the Yandex.Weather homepage in the weather card and in the detailed forecast.

Wind

Wind direction

The arrow indicates wind direction:

  • — North wind (blows from north to south).
  • — South wind (blows from south to north).
  • — West wind (blows from west to east).
  • — East wind (blows from east to west).

Wind speed

Measured in meters per second (m/s) using an anemometer.

Yandex.Weather shows the speed of wind at a height of 10 m above the Earth's surface.

Wind speed is affected by:
  • Difference between the atmospheric pressure and temperature in different layers of the atmosphere.
  • Uneven heating of the underlying surface.
  • Terrain features (mountain, forest, or city).
Wind speed, m/s. Wind force in Yandex.Weather

0

Calm

1-5

Light

6-10

Moderate

more than 10

Strong

Wind speed, m/s. Wind force in Yandex.Weather

0

Calm

1-5

Light

6-10

Moderate

more than 10

Strong

For more information about wind speed ranges, see the Beaufort Scale. This is an international scale for measuring wind speed on land and at sea.

Note. The web version of Yandex.Weather shows the average wind velocity, while the mobile version shows both the average and maximum wind speed (gust velocity) in the detailed forecast.