Global Precipitation & Temperature Outlook July 2018

2 July 2018

The July Outlook indicates exceptionally drier than normal conditions for most of southern Mexico into Central America. Much warmer than normal temperatures are forecast for Ireland and western United Kingdom, as well as many other parts of the world.

As seen in the precipitation map below, exceptionally drier than normal conditions paint a bright red path through much of Mexico's southern half and into Guatemala, El Salvador, western Honduras, and Costa Rica. Similarly intense dry anomalies are forecast for Tamaulipas in northeastern Mexico, while on the Pacific coast some moderate wet anomalies are forecast for the Baja Peninsula and western Sonora. Relatively normal precipitation is expected in the US and Canada, though some wet anomalies are forecast for the US Rockies and Southwest.

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.

In South America, some wet anomalies are forecast in pockets across the north, including Colombia, Venezuela, Guyana, French Guiana, and parts of the northern Amazon Basin in Brazil. Anomalies may be intense in Apure, Venezuela and northern Guyana. A few pockets of intense dry anomalies are also expected, near Caracas, Venezuela and in northern Colombia. Elsewhere on the continent, primarily moderate dry anomalies are forecast for southern Ecuador, central Peru, scattered across northern Bolivia, and Mato Grosso, Brazil. Moderately wetter than normal conditions are forecast for the Gran Chaco region of northern Argentina.

In Europe, moderate to severe dry anomalies are expected in the northern UK, northern Germany, and southern Norway and Sweden. Western France is forecast to be moderately wetter than normal, as are Italy's Piedmont region and northern Spain, and to a lesser extent, Greece and Macedonia.

In Africa, wet anomalies ranging from moderate to extreme are forecast for southern Cameroon, eastern Gabon, Republic of the Congo, across central Democratic Republic of the Congo, eastern Zambia, southern Tanzania, northern Malawi, western Mozambique, Zimbabwe, and into Botswana. Some wet anomalies are also forecast for Chad, reaching into Niger and Sudan, and in northern Algeria. Drier than normal conditions are forecast for western Ethiopia with some severe pockets expected.

Moderate to severe dry anomalies are forecast for the Don and Lower Volga River regions of Russia and into western Kazakhstan.

Wet anomalies reaching exceptional intensity in some areas are forecast across western China and in central China. North Korea will be moderately wetter than normal as will southern Myanmar and central Laos. Severe wet anomalies are forecast for Hokkaido, Japan.

In Europe, much warmer than normal temperatures are forecast for Ireland and western United Kingdom, with moderate to severe warm anomalies in Central Europe and southern Norway and Sweden. Some cooler than normal conditions are expected in Greece and across the Aegean Sea into northwestern Turkey and along Turkey's northern coast. Eastern and much of southern Turkey will see much warmer than normal conditions.

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.

Warm anomalies of varying intensity are forecast for most of northern Africa and also in Madagascar, where anomalies may be intense. In central Africa, however, conditions are expected to be much cooler than normal in Democratic Republic of the Congo, South Sudan, and eastern Uganda into western Kenya.

In the Middle East, conditions in the Levant will be moderately warmer than normal, but elsewhere in the region intense anomalies are forecast for Saudi Arabia, United Arab Emirates, western and southern Iraq, and western Iran. 

Intense warm anomalies will lead around the eastern Caspian Sea into western Turkmenistan, Uzbekistan, and Kazakstan, with moderate anomalies inland. Cool anomalies are forecast for Tajikistan.

Primarily moderate warm anomalies are forecast for southern India and Bangladesh but conditions may be slightly more intense in India's Far Northeast and in eastern Jammu and Kashmir. 

Southeast Asia and the Pacific are forecast to be moderately warmer than normal overall.

Warm anomalies of varying severity are forecast for eastern Russia, Mongolia, Inner Mongolia, Northeast China, Southeast China, Tibet, and Honshu, Japan. Anomalies may be extreme to exceptional in Far East Russia, Mongolia, and pockets of Tibet and Southeast China.

Conditions near Brisbane, Australia and on South Island, New Zealand are expected to be moderately warmer than normal.

In the West, warmer than normal temperatures are expected in the eastern half of the US and in the US West, while relatively normal conditions will prevail in the Plains. Several regions may see exceptional warm anomalies, including the Northeast, northern Louisiana and Arkansas, and southern Arizona. In Canada, warm anomalies are expected in the West and from southern Ontario eastward through New Brunswick. Temperatures in Nova Scotia will be exceptionally warmer. Around the southern shores of Hudson Bay, conditions will be much cooler than normal.

In Mexico, intense warm anomalies are expected in Baja, Nayarit, and coastal Oaxaca and Chiapas. Much cooler than normal temperatures are forecast for central Mexico. Southern Guatemala will be moderately warmer, as will El Salvador. Cooler conditions are forecast for central Honduras and south into Nicaragua.

In South America, moderate warm anomalies are forecast for western Colombia, Ecuador, southern Venezuela, southern Guyana, Suriname, and the Amazon Basin in Brazil. Severe to exceptional warm anomalies are expected in Maranhão, Brazil and in the country's easternmost region. A long line of exceptionally warmer than normal temperatures is also forecast along western Peru and into southwestern Bolivia, and pockets of northern Chile into northwestern Argentina. Some intense cool anomalies are forecast for northeastern Venezuela.

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 July 2, 2018 which includes forecasts for July 2018 through March 2019 based on NOAA CFSv2 forecasts issued June 24 through June 30, 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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