Precipitation, mostly rains, has a huge impact on agriculture. For plants to grow, they need at least a small amount of water, and rain is still one of the most effective ways of watering despite the development of modern technologies.

Too much or too little precipitation is bad and even harmful for agricultural plants. Drought can destroy the harvest and increase erosion, and overly humid weather can trigger the growth of unfavourable fungi. Also, different kinds of plants demand different amounts of precipitation. For example, some succulent species require little water, while tropical plants need hundreds of inches of rain a year just to continue living.

The fluctuation in precipitation amounts is quite substantial in continental climates. They fluctuate more in a month than during a year. A considerable variation in precipitation leads to situations where drought takes place during the years with low amounts, thus forming areas of unstable hydration. With a long absence of rains and at high temperatures, the reserves of moisture in the soil dry out due to evaporation.

A previous arid season brings a shortage of crop yield even in a humid season, as the harvest lacks enough time for ripening. Thus disadvantageous conditions for ordinary plant development are established, and the crop yield of agricultural plants decreases or perishes.

Along with precipitation amounts, the number of days with precipitation in a month or a year is also a significant climatic index. Plants are sensitive to whether a given precipitation amount falls all at once during just a few days, or it rains often and the amount is distributed comparatively evenly throughout a month. For instance, even one great downpour in a prairie area in summer has little ability to improve an arid situation.

By employing a data set of precipitation amounts and a number of days, one can calculate an accumulated precipitation amount for any region during a specific period of time.

Temperature, and especially accumulated temperature, is an important factor and plays a fundamental role in agricultural productivity. Plants and insects develop in accordance with the temperature. The warmer the weather, the faster they grow and reproduce; the colder it is, the more slowly these processes go.

All species have a biological minimum temperature level, below which development does not take place at all. When the temperature of the environment begins to exceed this minimum level, it gives a start to growth and reproduction. The value of this basic temperature (or a development threshold) has a crucial significance, and it differs between species of plants and insects.

Accumulated temperature (AT) represents an integrated excess or lack of temperature in relation to a fixed starting point. This index is calculated as the sum of the average daily temperatures of air and soil, above a chosen threshold of 0°C, 5°C or 10°C, or a biological minimum temperature level.

Basically, this is a way of including temperature and time into one dimension for quantitative evaluation of the speed of growth of plants and insects. Usually the index of accumulated temperature data is used to create models of crop growth.

In the near future, we will introduce our new API for accumulated temperature data. It will be based on historical data, and will be focused primarily on users in the agricultural sector.

We are happy to announce that one of our products – API for UV-index – has been significantly improved.

• Now, as well as current and historical data, you can also get UVI forecasts for periods of 8 days.
  
• The syntax has been made considerably easier: it has become clearer and more unified, like other API versions.
  
• There is a new feature to request data for any geographic coordinates without limits on accuracy.
  
• The accuracy level of the UVI modelled data has been doubled (the interpolation grid step has been reduced from 0.5 to 0.25 degrees).  
  
• Soon, searching by city/town name, city/town ID and postal/ZIP code will be available.

You can find the instructions for the updated version at http://openweathermap.org/api/uvi.

Access to the UV-index data will be available for all our plans. For more information on our plans, please visit http://openweathermap.org/price.

The previous version of the API (http://openweathermap.org/api/old-uvi) will soon be announced as deprecated, and no further support will then be provided for this version.

Do you want to receive weather data in your language? We have extended the list of supported languages for weather conditions.

Now the following languages are available in our API:

Arabic (ar); Czech (cz); Greek (el); Persian (Farsi) (fa); Galician (gl); Hungarian (hu); Japanese (ja); Korean (kr); Latvian (la); Lithuanian (lt); Macedonian (mk); Slovak (sk); Slovenian (sl); Vietnamese (vi).

We invite our users to test translations for weather conditions in different languages. We will be happy to extend our language support according to your wishes. If you have any questions or suggestions, please send them to https://openweathermap.desk.com/. The specification for all weather conditions is available here: http://openweathermap.org/weather-conditions.

We have added new versions of the rendering styles for the Weather Maps API.

To get the weather map layers in the new predefined styles, you need to add _new to the appropriate layer name, as follows:

http://tile.openweathermap.org/map/{layer}_new/{z}/{x}/{y}.png?appid={api_key}

For your convenience while working with our historical data, we have created the History Bulk section at OpenWeatherMap.com. There you can find a manual on extracting data for different time periods and cities/towns; there are also examples of data extraction in JSON and CSV file formats, and descriptions of weather parameters.

We are happy to introduce to you our new service that provides historical weather data for more than 30,000 cities/towns for the last 5 years.

Now you can simply choose a city/town (or several cities/towns) and download an archive, which contains a bulk file with the weather history for up to 5 years – any day or week, or even several years. Pricing is simple and easy – just $10 for one city/town, no matter how much data you receive – see http://openweathermap.org/price.

Just sign in and place an order on your personal page at https://home.openweathermap.org/history_bulks/new. Please note that our traditional History API stays the same.

One of the benefits of the VANE platform is that there is no need to search by scenes and footprints. It is based on a simple assumption: each location in the world has metadata – click on any location and you can get information about all pixels containing this location.

Such projects as cloudless atlases and Google base satellite maps are created according to this basic principle, stitching the best imagery pixels in one seamless mosaic. Based on the scene’s metadata, VANE can choose the best satellite cover – you need to set up a parameter “order=best” for this operation.

As well as this, the VANE language allows you to set up further requirements for your mosaic, providing appropriate parameters in your query:

no older than (“day>{yyyy-mm-dd}”)

or put all the latest imagery on the top (“order=last”)

or within a specific time interval (“between({yyyy-mm-dd}:{yyyy-mm-dd})”).

Then you can go further, applying your custom colours to the result mosaic, according to the VANE language specification.

Just to demonstrate this principle at work, we’ve launched a very basic application called Finder.

We invite you to try our new product, Weather Alerts – it provides weather alerts based on our meteorological data.

Now you can use simple syntax to create triggers, which will work upon the occurrence of specified weather conditions (temperature, humidity, pressure, etc.) in a certain period of time. For example, if you are interested in forecasts of the approach of frosts or the probability of strengthening of wind in a certain place, you can get this information by using our new tool.

The alerts will be generated in our service when the conditions for the trigger are satisfied. You will need to poll the service within a certain time interval in order to receive them. For the future, we are planning to improve and develop this service, with the addition of push notifications and new data sources.

You can find out more at http://openweathermap.org/triggers.

Weather Alerts structure: http://openweathermap.org/triggers-struct.

In the current version of the VANE Language, we use images from the Landsat 8 satellite, which captures the Earth’s entire surface every 16 days. The satellite makes hundreds of images, with a unique name for each one (such as “LC81410552016219LGN00”) and a pixel size of 30 metres. Each image consists of 11 bands; the size of an uncompressed image is 2 GB.

Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) images consist of nine spectral bands with a spatial resolution of 30 metres for Bands 1 to 7 and 9. New Band 1 (ultra-blue) is useful for coastal and aerosol studies, and also new Band 9 is applicable for cirrus cloud detection. The resolution of Band 8 (panchromatic) is 15 metres. Thermal Bands 10 and 11 provide more accurate surface temperatures and are collected at 100 metres. The approximate scene size is 170 km north–south by 183 km east–west (106 by 114 miles).

By default, we get Bands 2, 3, 4, 5 and 7, but it is possible to download any other bands.