Global Precipitation & Temperature Outlook August 2018

3 August 2018

The August Outlook indicates much warmer than normal temperatures in much of Europe reaching exceptional intensity in parts of Central Europe and southern Scandinavia. Precipitation is expected to be above average in Greece, Italy, and across the Mediterranean into Algeria.

In Europe, wetter than normal conditions are forecast for Italy, Greece, and along the French Riviera, and may be extreme (20 to 40 year return period) in mainland Greece and on Sicily. Eastern Europe may see some moderately drier than normal conditions, as will England, while severe dry anomalies (10 to 20 year return period) are forecast for Netherlands and across the border into northwestern Germany. Moderate to severe dry anomalies are forecast for the Caucasus and North Caucasus. 

Precipitation outlook. Reds indicate below normal monthly total precipitation. Blues indicate above normal monthly total precipitation. The darker the color, the more extreme the anomaly relative to a 1950-2009 climatic baseline. Colors are based on the expected return period of the anomalies.

Algeria is expected to be wetter than normal, particularly in the north, and wet anomalies will reach across Algeria's borders into surrounding countries. Scattered mild to moderate wet anomalies are forecast in Africa for: central Chad; eastern Burkina Faso, its southern neighbors, and western Nigeria; southern Cameroon into northern Republic of the Congo; Democratic Republic of the Congo; southern Uganda; Tanzania; and central South Africa. Central South Sudan may be somewhat drier than normal.

Relatively benign precipitation conditions are forecast in the Middle East. Dry anomalies are, however, forecast along Turkey's northern shore, along with pockets of wet anomalies in the southwest and east.

Likewise, South Asia and Southeast Asia are expected to be relatively normal with some pockets of extreme dry anomalies in northern Pakistan; northwest Bihar, India; southern Laos; central Vietnam; and eastern Cambodia. Moderate wet anomalies are forecast for Thailand's northeastern provinces, and some mild wet anomalies in New Guinea.

Vast pockets of western China are forecast to be wetter than normal, reaching exceptional intensity in parts of Xinjiang and Gansu, while primarily moderate wet anomalies are expected in southeast China and Taiwan. Southern Mongolia will be wetter than normal with some severe to extreme anomalies, while conditions in the northwest will be much drier, reaching into Russia. Moderate dry anomalies are forecast in Russia's eastern regions of Amur and Primorsky, and mild wet anomalies are forecast from the Yenisei Gulf to the Khatanga Gulf in northern Russia.

In South America, wet anomalies are forecast for eastern Colombia into Venezuela, north-central Guyana, western Brazil, and southern Brazil from the State of Paraná through Rio de Janeiro. Anomalies may be extreme in eastern Venezuela. A few small, isolated drier-than-normal pockets are forecast in northern Colombia and near Caracas, Venezuela.

Northwestern Mexico will be wetter than normal, with pockets trailing south along the coast through Jalisco, and farther south in coastal Oaxaca. Some dry anomalies are forecast for primarily Gulf regions of the Yucatan. Northeastern Honduras is forecast to be exceptionally drier than normal, while southeastern Guatemala will be wetter.

The US Southwest and Southeast will be wetter than normal, including Southern Appalachia to the Gulf and Florida, with anomalies ranging from moderate to severe.  Relatively normal conditions are forecast for Canada, though parts of Nunavut may be wetter than normal.

Most of Europe will be much warmer than normal with anomalies reaching exceptional intensity in parts of Central Europe and southern Scandinavia, particularly Wales, Belgium, Netherlands, northeastern France, western Germany, and southern Sweden. Further south, exceptional warm anomalies are also expected in Corsica and Sardinia. Moderate warm anomalies are forecast in western European Russia. 

Temperature outlook. Reds indicate above normal monthly average temperature. Blues indicate below normal monthly average temperature. The darker the color, the more extreme the anomaly relative to a 1950-2009 climatic baseline. Colors are based on the expected return period of the anomalies.

Northern Africa is forecast to be warmer than normal, with anomalies in Algeria, Libya, northern Niger, much of Egypt, and northern Sudan. Conditions will be exceptional from southeast Algeria through southern Libya and into southwestern Egypt, as well as in the Nile Delta. Intense warm anomalies are also expected in: parts of the Horn of Africa including eastern Ethiopia and Somalia; southeastern Kenya; from eastern Angola into western Zambia, Zimbabwe, Botswana, and northeastern Nambia; much of Madagascar; and southern Côte d'Ivoire into coastal Liberia. Moderately warmer than normal regions of Africa include: Cameroon, the Ethiopian Highlands, and parts of Tanzania and Mozambique.

Cooler than normal conditions (10 to 40 year return period) are forecast for much of the Lualaba River region of the Democratic Republic of the Congo; the central border area of Uganda and Kenya; and central South Sudan. 

In the Middle East, much of the Arabian Peninsula is forecast to be warmer than normal, ranging from moderate to pockets of extreme intensity. Basrah Province in southern Iraq will be exceptionally warmer than normal, with conditions nearly as intense in Kuwait, and moderately warmer temperatures in northwestern Iraq. Primarily moderate warm anomalies are expected in the bulk of Iran, though conditions may be more intense in Persian Gulf provinces and in Golestan Province in the north. Much cooler than normal temperatures are expected in a pocket of southeastern Iran. In Turkey, much cooler conditions are forecast along the Black Sea coast, while southern Turkey will be warmer than normal.

In Central Asia, moderate warm anomalies are forecast for southern Turkmenistan and Tajikistan, and cool anomalies in eastern Kyrgyzstan. Relatively normal conditions are forecast for South Asia with severe warm anomalies in northernmost Pakistan into India; primarily moderately warmer temperatures in southern India, India's Far Northeast, and Sri Lanka; and some cool anomalies in western India into Pakistan, and in a portion of the central Gangetic Plain south of Nepal.

Northwest Mongolia will be much warmer than normal, and comparable anomalies are expected nearby in northwestern China. Exceptional warm anomalies (40+ years return period) are expected in the central Tibetan Plateau. Northeastern China will be somewhat warmer than normal but conditions may be more intense around the Bohai Sea. Severe warm anomalies are forecast for southern Japan with conditions reaching exceptional intensity on Shikoku. 

Mild to moderate warm anomalies are forecast for Southeast Asia, Malaysia, Indonesia, and New Guinea. Queensland, Australia will be warmer than normal with extreme to exceptional anomalies near Brisbane and Sunshine Coast. Intense warm anomalies are also forecast for South Island, New Zealand.

In South America, central and eastern Brazil can expect moderate to exceptional warm anomalies. Extreme warm anomalies are forecast for southeastern Bolivia. Warm anomalies of varying intensity are expected along the Pacific tracing a path from Peru through central Chile. From Oaxaca, Mexico through Guatemala, Belize, El Salvador, and western Honduras, moderate to severe warm anomalies are forecast. Costa Rica and Panama will be moderately warmer than normal. Conditions on the Baja Peninsula will be more intense, but across the Gulf of California parts of northwestern mainland Mexico will be much cooler than normal.

The US Northeast can expect much warmer than normal temperatures - anomalies ranging from severe to exceptional - particularly in Maine. A pocket of intense warm anomalies is forecast for Louisiana and Mississippi, becoming moderate in surrounding states. Temperatures are expected to be much warmer than normal in Arizona, and moderate to severe warm anomalies will reach west through southern California and north into the Rocky Mountain states. Eastern Canada will be warmer than normal, with exceptional anomalies in the Maritime provinces.

There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

Each week, ISciences processes an ensemble of 28 seasonal temperature and precipitation forecasts issued by the National Oceanic and Atmospheric Administration's Climate Forecast System Version 2 (CFSv2). We present our results in a proprietary weekly report titled Global Water Monitor and Forecast: Precipitation and Temperature Outlook. This blog post summarizes our Outlook released August 2, 2018 which includes forecasts for August 2018 through April 2019 based on NOAA CFSv2 forecasts issued July 25 through July 31, 2018.

Technical details:

  • Each CFSv2 forecast is bias corrected by:
    • Constructing probability density functions from CFSv2 hindcasts.
    • Fitting the hindcast probability distribution functions to a generalized extreme value distribution.
    • Using an inverse lookup to an extreme value distribution fitted to the observed temperature and precipitation record (Fan & van den Dool 2008, Chen et al. 2002).
  • The map colors depict the return period of the median forecast anomaly.
  • Regions where the interquartile range of the ensemble spans both above normal and below normal conditions are hashed as having uncertain direction.
  • Regions where the interquartile range of the ensemble divided by the median forecast is large (>0.4) are hashed as having uncertain magnitude.
  • Results are reported in terms of return period using a 1950-2009 baseline.

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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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