Fields and gardens are complicated ecosystems in fact, and they are the perfect habitat for pests. Additionally to direct harm caused to plants by pests, many pest species can transmit viruses from one plant to another and hence spread diseases.
Biology of living creatures is closely connected with weather. Organisms are dependent on seasonal cycles as well as on temporary fluctuations. Weather influences all living things primarily due to changes in temperature and humidity. Weather conditions can provoke a sharp increase in pest amount. For example, hot and dry weather gives rise to aphid, while slugs and snails thrive in relatively warm and wet conditions. Pest behavior is especially closely bound to temperature. Aftermath of non-seasonal changes in temperature (such as later than usual frosts or warmer summers) and its impact on pests is notorious for many centuries.
Uncommonly high temperatures facilitate greater plant productivity, however at the same time they give a way to an additional generation of some pests during a vegetation period and thus to multiplication of pest amount.
Fortunately, carnivores are also connected with temperature changes and they respectively react to an increase in food amount by growth of their population what regulates a situation to some extent. And vice versa, colder periods, especially off a season, can significantly decrease pest populations eliminating either pests that have just exited hibernation or a newly spring breed.
Unfortunately, beneficial carnivorous species can perish in these conditions too that would have an impact on their population next year and consequently on growth of pest amount. Day heating, night cooling and related to it day variations of light intensity often result in activity peaks of different pest kinds happening at a peculiar time of the day.
Many species of pests have threshold temperatures below which they are inactive. Knowing these threshold values and having information about temperature for a recent time span, one can forecast a situation quite precisely and take timely actions to control both the amount of pests and their adversaries.
One of the most convenient parameters which enables forecasting a way of pest development is accumulated temperature. All species have a threshold temperature that brings growth and a threshold minimum when development halts. These data let define a starting point of reproduction and growth of various pest kinds, forecast an increase in amount of pest breeds over a season and thus evaluate a potential damage and take necessary measures to diminish this harm to a large extent.
OpenWeatherMap provides such data in the form of convenient to use API. API for accumulated temperature data is based on historical data. This index is determined as the sum of average daily air and soil temperatures which exceeds a definite threshold of 0, 5, 10 degrees or a biological minimum of a temperature level which is crucial for some specific plant.