Weather and climate are among the major risk factors with the potential to impact upon farming performance and management. Extreme weather and climate events such as severe droughts, floods, or temperature shocks can often strongly impede sustainable farming development, particularly in the tropics and sub-tropics. Factors such as climate variability and change can contribute to the vulnerability of individual farms, as well as that of entire rural communities. These factors can also have particular impact on regional and global food security. Recent weather and climate research efforts have demonstrated the importance of targeted forecasting and scenario analysis as a way to increase the overall preparedness of farmers and farm business managers, which contributes substantially to the improvement of overall outcomes.

Decision-making in agricultural production is a complex process in which many risks need to be con-sidered for an informed decision to be made. In many parts of the world, weather and climate are one of the biggest production risks and uncertainty factors impacting on agricultural systems performance and management. Farmers around the world, especially those in the developing countries, have been trying to adapt to the variable weather and climate conditions through various risk-management strategies. Improved weather and climate information, supplied to the farming community in a timely manner, can greatly assist the farmers in their operational decisions.

Challenges in linking meteorological and climatological information with a wide range of farming decisions are addressed in this paper. In particular, while a considerable amount of weather and climate information is now available for farmers, some types of information under development or already operational, particularly climate forecasting, formation, may be ill-suited for use by farmers for their decision-making. Case studies show it is particularly important for those key farm decisions that are amenable to weather and climate information to be identified clearly so that weather and climate information can be better tailored to suit farming decisions. A participatory approach provides farmers with ownership of the processes associated with development of weather and climate information and facilitates advances in linking climate and weather information and forecasts to farm decisions. Decision-support systems provide useful output when used with farmer discussion groups. Developing appropriate interdisciplinary systems to connect climate, weather, and agronomic information, especially including forecasting systems, with farm management is needed if uptake of weather and climate information by farmers is to be successful. Provision of output of climate change scenario and trend information to aid long-term strategic farm management decisions needs to be considered, especially in regions where more vulnerable farming zones exist.

Agrometeorological information and services from the National Meteorological and Hydrological Services (NMHSs) are increasingly being demanded by the farming community to cope more efficiently with climate variability and the increasing incidence of extreme meteorological events such as droughts, floods, frosts and wind erosion. While considerable advances have been made in the collection, archiving and analysis of weather and climate data, their transformation into information that can be readily used by the farm sector has lagged behind, especially in developing countries where such information needs are the greatest. One of the important reasons is the lack of adequate interaction with the user community in assessing the appropriate dissemination and communication procedures that can enhance the value of the agrometeorological information and services. A brief review of the present status of dissemination and communication of agrometeorological information by the NMHSs and associated agencies in different regions around the world is presented. A description of the user communities for agrometeorological information and their varying needs is also presented. Opportunities and challenges in the dissemination and communication of agrometeorological information by the NMHSs are described with suitable examples which emphasize that continued improvements are necessary to make agrometeorological information more accessible and useful to the user community.

There are many challenges facing today's farmers and the use of weather and climate can help farmers in meeting and overcoming these challenges. Additionally, government decision-makers use information on actual and potential crop production impacts, a large percentage of which is based on weather and climate information such as drought, heavy rain events, and hurricanes. The Joint Agricultural Weather Facility (JAWF) is an example of one U.S. Government organization successfully using weather and climate information in many of its operational applications that are disseminated to users. These agricultural weather applications or products are grouped into tactical (short-term) and strategic (long-term) products. Examples of tactical products discussed include the Weekly Weather and Crop Bulletin (WWCB); routine and special crop-weather assessments, and a Regional Weather Network in Mississippi. Strategic products discussed include the U.S. Drought Monitor and the use of weather information in the monthly World Agricultural Supply and Demand Estimates (WASDE) process. The purpose of this paper is to provide some successful applications of climate and weather information and how this information is communicated between this agrometeorological service and farmers. Also, the goal is to provide lessons learned for other agrometeorological services around the world.

During an Inter-Regional Workshop on Improving Agrometeorological Bulletins in Barbados in October 2001, participants recommended that a dedicated web server be developed for distributing agrometeorological products from WMO members. Subsequently, an Expert Group Meeting on Internet Applications for Agrometeorological Products was held in Washington, DC, during May 2002, to discuss the practical steps needed to develop this web server. Discussions from this meeting led to the development of the World AgroMeteorological Information Service (WAMIS). WAMIS is a dedicated web server on which countries and organisations can place their agrometeorological bulletins and advisories. Provision of such a central location for agrometeorological information enables users to quickly and easily evaluate various bulletins and gain insight into improving their own bulletins. Also, these bulletins represent the expert knowledge of the individual countries and provide the possibility to assess extreme events and disasters in a historical perspective, especially when an archive of bulletins is present. Placement of agrometeorological bulletins on WAMIS also increases the visibility of the National Meteorological/Hydrological Services (NMHS). In March 2005, a tools and resources section was added to WAMIS to provide users with additional papers, links to software tools, Internet links, and other resources to help improving their agrometeorological bulletins and advisories and services.

Food insecurity represents one of the main indicators of the poverty level of a country and can breed a strong dependence on foreign aid with a strong slowdown of the national economy. African arid and semi-arid areas are characterised by food precariousness and their agricultural activity is strongly dependent on the extreme climatic conditions that affect the available water supply. This situation has led to the need to develop new tools for the prediction and the management of crisis. The characterisation of climate and the identification of anomalies, the monitoring of weather conditions and their influence on crops, short and medium range weather forecasts and long-term climate predictions are among the most powerful tools to predict, in as short a time as possible, crises due to the absence or delay of rainfall season. Meteorological information can also be used as an input to agrometeorological models applied for crisis prevention or for its management during the growing season when the crops are already present. In this paper, a review of these tools is made and some operational products presented.

Agroclimatology represents the link between several agrometeorological fields and climatological applications. The German Weather Service (DWD) uses data from many meteorological stations for 40-year calculations by agrometeorological models. The topics extend from microclimatic elements over the wide field of soil conditions and water content, agricultural operations and product quality to forest fires and plant pests. Analyses of agroclimatic output allow for better planning, risk assessment, objective evaluation of the current situation and even for a test of the models used. Current applications concern crop microclimate, including soil, evapotranspiration and volatilisation, plant protection, phenology and product quality, with examples such as the frequency of extreme soil frost, optimum harvest conditions, plant water stress on different soils, and the frequency of high pest incidence. Not only singular places, but regions too can be evaluated. Results from combinations of elements, such as soil frozen with high water content, are considered valuable for recommendations to agricultural users. Agroclimatic model information concerning, for example, removal of plastic cover from spring crops, soil conditions for plant water use, tractability, herbicide effectiveness, germination, nutrient washout, and harvest, is directly usable by farmers. The information about forest fire index, extreme season assessment (for compensation payments), and trend analyses is of practical use for administration. The use of risk levels for plant pathogens is important both for farmers and extension services. The future importance of agroclimatic applications is considered high.

If mean temperature increases, in accordance with Intergovernmental Panel on Climate Change (IPCC) projections and adaptations and/or genetic modifications are not considered, suitable areas for farming corn (Zea mays) and coffee (Coffea arabica) will decrease in the state of Sao Paulo (Brazil). Further, increases in precipitation will not be enough to ameliorate the impacts associated with increases in mean temperatures. Suitability for grain production will decrease more rapidly in regions with sandy soils than in regions with clay or medium soils, as the temperature increases. The projected increase in mean temperature of up to 5.8°C would decrease the suitability for grain production drastically in spite of soil texture. Besides the reduction of suitable areas for coffee production, the projections suggest that changes will be more enhanced in the southeast of the state, especially in higher elevation regions, where farming practice, soils, and infrastructure are unsuitable for the economic production of coffee. In both cases, no compensatory increase in suitable areas for production is likely under current IPCC scenarios.

Fruit growing in Slovenia has become one of the more important agricultural production branches over the last two decades. Due to climate variability over a relatively small area of 20,000 km2, irrigation practices are not only important but also indispensable agrotechnical measures for obtaining permanent, high quality crop yields in the northeastern and southwestern parts of the country. Hence, accurate estimation of water consumption by agricultural crops with the inclusion of metorological monitoring is essential in the field of water management. As a decision support tool, the Slovenian Agrometeorological Information System (SAgMIS) developed by Agrometeorological Department in the Environmental Agency of the Republic of Slovenia (EARS) and introduced 10 years ago has improved significally over the last two years. Transfer of actual and forecasted agrometeorological data to the end users has been quick and accurate, with the last version of mobile data dissemination in testing use. A case study of water use by irrigated peach trees in the plantation orchards of lower Vipava valley was undertaken from 1996 to 2004. A variety of irrigation systems with diverse irrigation water applications was introduced for the purposes of studying irrigation water benefits derived from accurate weather data and forecasts. The results showed that important savings in the amount of irrigation water used, on an annual average of 20%, could be achieved with accurate and timely irrigation forecasts during the vegetation periods.

Research was performed in Poggio Casciano Estate (Chianti area, central Italy) with the aim of defining a general approach to analyse the spatial variability of temperature at the microscale. Hourly data were collected from a network of 27 temperature stations covering an area of about 120 ha and determination coefficients r between station pairs on the basis of different geo-topographical factors were calculated. The data were analysed in order to investigate trends describing the spatial distribution of temperature inside the study area. The results pointed out a strong effect of some topographical condition on the distribution of thermal patterns, in particular altitude and the distance from valley bottoms. The results are discussed in order to formulate a general approach for the characterisation of climatic conditions at small scale.