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.