Editing Geography of Chad (section)

==Climate==
[[File:Koppen-Geiger Map TCD present.svg|thumb|Chad map of Köppen climate classification]]
{{See also|Chad#Climate}}
[[File:Voiture pendant la saison de pluie au Tchad.webm|left|thumb|Car facing difficulties during rain season]]
The Lake Chad Basin embraces a great range of tropical climates from north to south, although most of these climates tend to be dry.<ref name=":0" /> Apart from the far north, most regions are characterized by a cycle of alternating rainy and dry seasons.<ref name=":0" /> In any given year, the duration of each season is determined largely by the positions of two great air masses—a maritime mass over the Atlantic Ocean to the southwest and a much drier continental mass.<ref name=":0" />

During the rainy season, winds from the southwest push the moister maritime system north over the African continent where it meets and slips under the continental mass along a front called the "intertropical convergence zone".<ref name=":0" /> At the height of the rainy season, the front may reach as far as Kanem Prefecture.<ref name=":0" /> By the middle of the dry season, the intertropical convergence zone moves south of Chad, taking the rain with it.<ref name=":0" /> This weather system contributes to the formation of three major regions of climate and vegetation.<ref name=":0" />

===Saharan region===
[[File:Sand strom Chad.jpg|thumb|250px|A [[Dust storm|duststorm]] at Abéché airport, Chad (2005).]]
The Saharan region covers roughly the northern half of the country, including Borkou-Ennedi-Tibesti Prefecture along with the northern parts of Kanem, Batha, and Biltine prefectures.<ref name=":0" /> Much of this area receives only traces of rain during the entire year; at Faya-Largeau, for example, annual rainfall averages less than {{convert|12|mm|in|2|sp=us}}, and there are nearly 3800 hours of sunshine.<ref name=":0" /> Scattered small oases and occasional wells provide water for a few date palms or small plots of millet and garden crops.<ref name=":0" />

In much of the north, the average daily maximum temperature is about {{convert|32|°C|1}} during January, the coolest month of the year, and about {{convert|45|°C}} during May, the hottest month.<ref name=":0" /> On occasion, strong winds from the northeast produce violent sandstorms.<ref name=":0" /> In northern Biltine Prefecture, a region called the Mortcha plays a major role in animal husbandry.<ref name=":0" /> Dry for eight months of the year, it receives {{convert|350|mm|in|1|sp=us}} or more of rain, mostly during July and August.<ref name=":0" />

A carpet of green springs from the desert during this brief wet season, attracting herders from throughout the region who come to pasture their cattle and camels.<ref name=":0" /> Because very few wells and springs have water throughout the year, the herders leave with the end of the rains, turning over the land to the antelopes, gazelles, and ostriches that can survive with little groundwater.<ref name=":0" /> Northern Chad averages over 3500 hours of sunlight per year, the south somewhat less.

{{Weather box
|width = auto
|location = Faya-Largeau (1961–1990)
|metric first = yes
|single line = yes
|Jan record high C = 39
|Feb record high C = 43
|Mar record high C = 44
|Apr record high C = 49
|May record high C = 49
|Jun record high C = 49
|Jul record high C = 47
|Aug record high C = 46
|Sep record high C = 46
|Oct record high C = 47
|Nov record high C = 39
|Dec record high C = 36
|year record high C = 49
|Jan high C = 26.4
|Feb high C = 29.4
|Mar high C = 33.6
|Apr high C = 39.1
|May high C = 41.0
|Jun high C = 42.1
|Jul high C = 41.0
|Aug high C = 40.2
|Sep high C = 39.8
|Oct high C = 36.5
|Nov high C = 31.1
|Dec high C = 27.6
|year high C = 35.7
|Jan mean C = 20.0
|Feb mean C = 22.2
|Mar mean C = 26.0
|Apr mean C = 30.8
|May mean C = 33.0
|Jun mean C = 34.1
|Jul mean C = 33.4
|Aug mean C = 33.1
|Sep mean C = 32.7
|Oct mean C = 29.5
|Nov mean C = 24.5
|Dec mean C = 21.0
|Jan low C = 13.6
|Feb low C = 15.0
|Mar low C = 18.4
|Apr low C = 22.4
|May low C = 25.0
|Jun low C = 26.1
|Jul low C = 25.8
|Aug low C = 26.0
|Sep low C = 25.9
|Oct low C = 22.5
|Nov low C = 17.9
|Dec low C = 14.4
|year low C = 21.1
|Jan record low C = 4
|Feb record low C = 7
|Mar record low C = 11
|Apr record low C = 14
|May record low C = 17
|Jun record low C = 17
|Jul record low C = 16
|Aug record low C = 16
|Sep record low C = 17
|Oct record low C = 12
|Nov record low C = 9
|Dec record low C = 3
|year record low C = 3
|rain colour = green
|Jan rain mm = 0.0
|Feb rain mm = 0.0
|Mar rain mm = 0.0
|Apr rain mm = 0.1
|May rain mm = 0.4
|Jun rain mm = 0.3
|Jul rain mm = 3.0
|Aug rain mm = 7.0
|Sep rain mm = 0.8
|Oct rain mm = 0.1
|Nov rain mm = 0.0
|Dec rain mm = 0.0
|year rain mm = 11.7
|Jan humidity = 25
|Feb humidity = 20
|Mar humidity = 18
|Apr humidity = 18
|May humidity = 17
|Jun humidity = 20
|Jul humidity = 27
|Aug humidity = 33
|Sep humidity = 22
|Oct humidity = 25
|Nov humidity = 23
|Dec humidity = 25
|year humidity = 23
|unit rain days = 0.1 mm
|Jan rain days = 0
|Feb rain days = 0
|Mar rain days = 0
|Apr rain days = 1
|May rain days = 1
|Jun rain days = 1
|Jul rain days = 2
|Aug rain days = 3
|Sep rain days = 1
|Oct rain days = 1
|Nov rain days = 0
|Dec rain days = 0
|year rain days = 
|Jan sun = 306.9
|Feb sun = 291.2
|Mar sun = 306.9
|Apr sun = 309.0
|May sun = 344.1
|Jun sun = 333.0
|Jul sun = 334.8
|Aug sun = 319.3
|Sep sun = 312.0
|Oct sun = 319.3
|Nov sun = 309.0
|Dec sun = 306.9
|year sun = 3792.4
|Jand sun = 9.9
|Febd sun = 10.4
|Mard sun = 9.9
|Aprd sun = 10.3
|Mayd sun = 11.1
|Jund sun = 11.1
|Juld sun = 10.8
|Augd sun = 10.3
|Sepd sun = 10.4
|Octd sun = 10.3
|Novd sun = 10.3
|Decd sun = 9.9
|yeard sun = 10.4
|source 1 = [[World Meteorological Organization]] (temperatures and precipitation days)<ref name= WMO>{{cite web
| url = http://worldweather.wmo.int/en/city.html?cityId=1173
| title = World Weather Information Service–Faya-Largeau
| publisher = World Meteorological Organization
| access-date = June 24, 2015}}</ref>
|source 2 = NOAA (sun and humidity),<ref name= NOAA>{{cite web
| url = ftp://ftp.atdd.noaa.gov/pub/GCOS/WMO-Normals/TABLES/REG__I/TE/64753.TXT
| title = Faya–Largeau Climate Normals 1961–1990
| publisher = [[National Oceanic and Atmospheric Administration]]
| access-date = June 24, 2015}}</ref> ''[[Annales de Géographie]]''<ref name="annals">{{cite journal|title= Le Borkou. Aspects d'un modèle éolien|journal= [[Annales de Géographie]]|year=1968|first=Monique|last=Mainguet|volume=77|issue=421|pages=296–322|doi= 10.3406/geo.1968.15662|url=http://www.persee.fr/web/revues/home/prescript/article/geo_0003-4010_1968_num_77_421_15662|language=fr}}</ref><ref>http://www.bbc.co.uk/weather/world/city_guides/results.shtml?tt=TT000120 {{Dead link|fix-attempted=yes|date=May 2019}}</ref>
}}

===Sahelian region===
The semiarid sahelian zone, or Sahel, forms a belt about {{convert|500|km|mi|0|sp=us}} wide that runs from Lac and Chari-Baguirmi prefectures eastward through Guéra, Ouaddaï, and northern Salamat prefectures to the Sudanese frontier.<ref name=":0" /> The climate in this transition zone between the desert and the southern sudanian zone is divided into a rainy season (from June to September) and a dry period (from October to May).<ref name=":0" />

In the northern Sahel, thorny shrubs and acacia trees grow wild, while date palms, cereals, and garden crops are raised in scattered oases.<ref name=":0" /> Outside these settlements, nomads tend their flocks during the rainy season, moving southward as forage and surface water disappear with the onset of the dry part of the year.<ref name=":0" /> The central Sahel is characterized by drought-resistant grasses and small woods.<ref name=":0" /> Rainfall is more abundant there than in the Saharan region.<ref name=":0" /> For example, N'Djamena records a maximum annual average rainfall of {{convert|580|mm|in|1|sp=us}}, while Ouaddaï Prefecture receives just a bit less.<ref name=":0" />

During the hot season, in April and May, maximum temperatures frequently rise above {{convert|40|°C}}.<ref name=":0" /> In the southern part of the Sahel, rainfall is sufficient to permit crop production on unirrigated land, and millet and sorghum are grown.<ref name=":0" /> Agriculture is also common in the marshlands east of Lake Chad and near swamps or wells.<ref name=":0" /> Many farmers in the region combine subsistence agriculture with the raising of cattle, sheep, goats, and poultry.<ref name=":0" />
{{Weather box
|location = N'Djamena (1961-1990, extremes 1904-present)
|metric first= Y
|single line= Y
|width = auto
|Jan record high C = 41.8
|Feb record high C = 47.6
|Mar record high C = 46.5
|Apr record high C = 48.3
|May record high C = 49.1
|Jun record high C = 44.0
|Jul record high C = 46.0
|Aug record high C = 38.6
|Sep record high C = 40.5
|Oct record high C = 43.6
|Nov record high C = 47.5
|Dec record high C = 40.5
|year record high C = 49.1
|Jan high C = 32.4
|Feb high C = 35.2
|Mar high C = 38.7
|Apr high C = 41.0
|May high C = 39.9
|Jun high C = 37.2
|Jul high C = 33.5
|Aug high C = 31.6
|Sep high C = 33.7
|Oct high C = 36.9
|Nov high C = 35.8
|Dec high C = 33.5

| Jan mean C = 23.4
| Feb mean C = 25.9
| Mar mean C = 29.9
| Apr mean C = 32.9
| May mean C = 32.9
| Jun mean C = 30.9
| Jul mean C = 28.3
| Aug mean C = 27.0
| Sep mean C = 28.2
| Oct mean C = 29.4
| Nov mean C = 26.8
| Dec mean C = 24.2
|year mean C = 
|Jan low C = 14.3
|Feb low C = 16.6
|Mar low C = 21.0
|Apr low C = 24.8
|May low C = 25.8
|Jun low C = 24.7
|Jul low C = 23.1
|Aug low C = 22.4
|Sep low C = 22.7
|Oct low C = 21.8
|Nov low C = 17.8
|Dec low C = 14.8
|year high C= 35.8 |year low C= 20.8
|year high F =96.4 |year low F =69.5<!--rounds down-->
|Jan record low C = 6.5
|Feb record low C = 8.0
|Mar record low C = 11.3
|Apr record low C = 16.2
|May record low C = 16.8
|Jun record low C = 18.2
|Jul record low C = 17.7
|Aug record low C = 18.5
|Sep record low C = 15.1
|Oct record low C = 13.5
|Nov record low C = 10.3
|Dec record low C = 8.4
|year record low C = 6.5
|rain colour = green
|Jan rain mm = 0.0
|Feb rain mm = 0.0
|Mar rain mm = 0.3
|Apr rain mm = 10.3
|May rain mm = 25.8
|Jun rain mm = 51.0
|Jul rain mm = 143.8
|Aug rain mm = 174.4
|Sep rain mm = 84.3
|Oct rain mm = 20.3
|Nov rain mm = 0.1
|Dec rain mm = 0.0
|year rain mm = 
|Jan humidity = 29
|Feb humidity = 23
|Mar humidity = 21
|Apr humidity = 28
|May humidity = 39
|Jun humidity = 52
|Jul humidity = 68
|Aug humidity = 76
|Sep humidity = 72
|Oct humidity = 49
|Nov humidity = 33
|Dec humidity = 31
|year humidity = 43
|unit rain days = 0.1 mm
|Jan rain days = 0
|Feb rain days = 0
|Mar rain days = 1
|Apr rain days = 3
|May rain days = 6
|Jun rain days = 9
|Jul rain days = 13
|Aug rain days = 15
|Sep rain days = 9
|Oct rain days = 3
|Nov rain days = 1
|Dec rain days = 0
|Jan sun = 297.6
|Feb sun = 277.2
|Mar sun = 282.1
|Apr sun = 273.0
|May sun = 285.2
|Jun sun = 258.0
|Jul sun = 213.9
|Aug sun = 201.5
|Sep sun = 228.0
|Oct sun = 285.2
|Nov sun = 300.0
|Dec sun = 303.8
|year sun = 3205.5
|Jand sun = 9.6
|Febd sun = 9.9
|Mard sun = 9.1
|Aprd sun = 9.1
|Mayd sun = 9.2
|Jund sun = 8.6
|Juld sun = 6.9
|Augd sun = 6.5
|Sepd sun = 7.6
|Octd sun = 9.2
|Novd sun = 10.0
|Decd sun = 9.8
|yeard sun = 8.8
|source 1 = [[World Meteorological Organization]] (precipitation)<ref name= WMOndjamena>{{cite web
| url = http://worldweather.wmo.int/en/city.html?cityId=256
| title = World Weather Information Service–Ndjamena
| publisher = World Meteorological Organization
| access-date = October 19, 2015
| archive-url = https://web.archive.org/web/20160304073518/http://worldweather.wmo.int/en/city.html?cityId=256
| archive-date = March 4, 2016
| url-status = dead
}}</ref>
|source 2 = NOAA (sun, humidity, temperatures),<ref name= NOAANdjamena>{{cite web
| url = https://www.ncei.noaa.gov/pub/data/normals/WMO/1961-1990/RA-I/TE/64700.TXT
| title = ND'Jamena Climate Normals 1961–1990
| publisher = [[National Oceanic and Atmospheric Administration]]
| access-date = October 19, 2015}}</ref> Meteo Climat (record highs and lows)<ref name = meteoclimatnjadema>
{{cite web 
| url = http://meteo-climat-bzh.dyndns.org/index.php?page=stati&id=1876
| title = Station N'Djamena
| publisher = Meteo Climat 
|language = fr 
| access-date = October 19, 2016}}</ref>
|date=September 2011}}

===Sudanian region===
The humid ''sudanian'' zone includes the [[Sahel]],<ref>{{cite book | last1=Gorse | first1=J.E. | last2=Steeds | first2=D.R. | title=Desertification in the Sahelian and Sudanian Zones of West Africa | publisher=[[World Bank]] | issue=v. 23-61 | year=1987 | isbn=978-0-8213-0897-4 | url=https://books.google.com/books?id=wAUSAQAAIAAJ | access-date=12 September 2019 | page=1}}</ref> the southern prefectures of Mayo-Kebbi, Tandjilé, Logone Occidental, Logone Oriental, Moyen-Chari, and southern Salamat.<ref name=":0" /> Between April and October, the rainy season brings between {{convert|750|and|1250|mm|in|1|sp=us}} of precipitation.<ref name=":0" /> Temperatures are high throughout the year.<ref name=":0" /> Daytime readings in Moundou, the major city in the southwest, range from {{convert|27|°C|1}} in the middle of the cool season in January to about {{convert|40|°C}} in the hot months of March, April, and May.<ref name=":0" />

The sudanian region is predominantly [[East Sudanian savanna]], or plains covered with a mixture of tropical or subtropical grasses and woodlands.<ref name=":0" /> The growth is lush during the rainy season but turns brown and dormant during the five-month dry season between November and March.<ref name=":0" /> Over a large part of the region, however, natural vegetation has yielded to agriculture.

{{Weather box
|width = auto
|location = Sarh (1961-1990)
|single line = Yes
|metric first = Yes
|Jan high C = 35.8
|Feb high C = 38.0
|Mar high C = 39.1
|Apr high C = 38.5
|May high C = 36.2
|Jun high C = 33.2
|Jul high C = 30.9
|Aug high C = 30.6
|Sep high C = 31.7
|Oct high C = 33.6
|Nov high C = 35.5
|Dec high C = 35.4
|year high C = 34.9
|Jan low C = 16.5
|Feb low C = 18.8
|Mar low C = 22.6
|Apr low C = 24.7
|May low C = 24.1
|Jun low C = 22.6
|Jul low C = 21.6
|Aug low C = 21.5
|Sep low C = 21.5
|Oct low C = 21.7
|Nov low C = 18.8
|Dec low C = 16.4
|year low C = 20.9
|rain colour = green
|Jan rain mm = 0.1
|Feb rain mm = 1.6
|Mar rain mm = 9.5
|Apr rain mm = 37.4
|May rain mm = 82.1
|Jun rain mm = 135.9
|Jul rain mm = 234.4
|Aug rain mm = 243.7
|Sep rain mm = 165.5
|Oct rain mm = 55.8
|Nov rain mm = 3.3
|Dec rain mm = 0.0
|year rain mm = 969.3
|Jan humidity = 33
|Feb humidity = 29
|Mar humidity = 37
|Apr humidity = 50
|May humidity = 61
|Jun humidity = 72
|Jul humidity = 79
|Aug humidity = 82
|Sep humidity = 80
|Oct humidity = 73
|Nov humidity = 57
|Dec humidity = 42
|year humidity = 58
|unit rain days = 0.1 mm
|Jan rain days = 0
|Feb rain days = 1
|Mar rain days = 2
|Apr rain days = 5
|May rain days = 9
|Jun rain days = 12
|Jul rain days = 15
|Aug rain days = 18
|Sep rain days = 16
|Oct rain days = 7
|Nov rain days = 1
|Dec rain days = 0
|year rain days = 86
|Jan sun = 266.6
|Feb sun = 243.6
|Mar sun = 244.9
|Apr sun = 237.0
|May sun = 241.8
|Jun sun = 207.0
|Jul sun = 173.6
|Aug sun = 176.7
|Sep sun = 186.0
|Oct sun = 232.5
|Nov sun = 261.0
|Dec sun = 266.6
|year sun = 2737.3
|Jand sun = 8.6
|Febd sun = 8.7
|Mard sun = 7.9
|Aprd sun = 7.9
|Mayd sun = 7.8
|Jund sun = 6.9
|Juld sun = 5.6
|Augd sun = 5.7
|Sepd sun = 6.2
|Octd sun = 7.5
|Novd sun = 8.7
|Decd sun = 8.6
|yeard sun = 7.5
|source 1 = [[World Meteorological Organization]] (temperatures and rainy days)<ref name= WMOSarh>{{cite web
| url = http://worldweather.wmo.int/en/city.html?cityId=1172
| title = World Weather Information Service – Sarh
| publisher = World Meteorological Organization
| accessdate = June 24, 2015}}</ref>
|source 2 = NOAA (sun, humidity and precipitation)<ref name= NOAAsarh>{{cite web
| url = ftp://ftp.atdd.noaa.gov/pub/GCOS/WMO-Normals/TABLES/REG__I/TE/64750.TXT
| title = Sarh Climate Normals 1961-1990
| publisher = [[National Oceanic and Atmospheric Administration]]
| accessdate = June 24, 2015}}</ref>
|date=November 2011
}}

{{Weather box
|width = auto
|location = Moundou (1961-1990)
|single line = Yes
|metric first = Yes
|Jan high C = 34.1
|Feb high C = 36.7
|Mar high C = 38.6
|Apr high C = 38.0
|May high C = 35.7
|Jun high C = 32.3
|Jul high C = 30.2
|Aug high C = 29.8
|Sep high C = 30.7
|Oct high C = 33.1
|Nov high C = 35.1
|Dec high C = 34.2
|year high C = 34.0
|Jan low C = 15.1
|Feb low C = 18.3
|Mar low C = 22.5
|Apr low C = 24.2
|May low C = 23.5
|Jun low C = 22.1
|Jul low C = 21.2
|Aug low C = 21.0
|Sep low C = 20.8
|Oct low C = 21.0
|Nov low C = 17.4
|Dec low C = 14.6
|year low C = 20.1
|rain colour = green
|Jan rain mm = 0.0
|Feb rain mm = 0.2
|Mar rain mm = 4.6
|Apr rain mm = 39.2
|May rain mm = 89.8
|Jun rain mm = 147.7
|Jul rain mm = 257.8
|Aug rain mm = 284.8
|Sep rain mm = 200.1
|Oct rain mm = 57.1
|Nov rain mm = 1.5
|Dec rain mm = 0.0
|year rain mm = 1082.8
|Jan humidity = 36
|Feb humidity = 28
|Mar humidity = 31
|Apr humidity = 50
|May humidity = 63
|Jun humidity = 73
|Jul humidity = 80
|Aug humidity = 81
|Sep humidity = 78
|Oct humidity = 73
|Nov humidity = 56
|Dec humidity = 45
|year humidity = 58
|unit rain days = 0.1 mm
|Jan rain days = 0
|Feb rain days = 1
|Mar rain days = 2
|Apr rain days = 5
|May rain days = 9
|Jun rain days = 12
|Jul rain days = 15
|Aug rain days = 19
|Sep rain days = 13
|Oct rain days = 7
|Nov rain days = 2
|Dec rain days = 0
|year rain days = 85
|Jan sun = 279.0
|Feb sun = 249.2
|Mar sun = 248.0
|Apr sun = 234.0
|May sun = 241.8
|Jun sun = 210.0
|Jul sun = 182.9
|Aug sun = 170.5
|Sep sun = 186.0
|Oct sun = 235.6
|Nov sun = 282.0
|Dec sun = 291.4
|year sun =
|Jand sun = 9.0
|Febd sun = 8.9
|Mard sun = 8.0
|Aprd sun = 7.8
|Mayd sun = 7.8
|Jund sun = 7.0
|Juld sun = 5.9
|Augd sun = 5.5
|Sepd sun = 6.2
|Octd sun = 7.6
|Novd sun = 9.4
|Decd sun = 9.4
|yeard sun = 7.7
|source 1 = [[World Meteorological Organization]]<ref name= MoundouWMO>{{cite web
| url = http://worldweather.wmo.int/en/city.html?cityId=1171
| title = World Weather Information Service – Moundou
| publisher = World Meteorological Organization
| access-date = June 24, 2015}}</ref>
|source 2 = NOAA (sun and humidity)<ref name= NOAAmoundou>{{cite web
| url = https://www.ncei.noaa.gov/pub/data/normals/WMO/1961-1990/RA-I/TE/64706.TXT
| title = Moundou Climate Normals 1961-1990
| publisher = [[National Oceanic and Atmospheric Administration]]
| access-date = June 24, 2015}}</ref>
|date=November 2011}}

===2010 drought===
{{Main|2010 Sahel drought}} 
On 22 June, the temperature reached {{convert|47.6|°C|°F}} in Faya, breaking a record set in 1961 at the same location. Similar temperature rises were also reported in [[Niger]], which began to enter a famine situation.<ref name="MastersNOAA">{{cite web|last=Masters|first=Jeff|title=NOAA: June 2010 the globe's 4th consecutive warmest month on record|url=http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1544|work=Weather Underground|publisher=Jeff Masters' WunderBlog|access-date=21 July 2010|url-status=dead|archive-url=https://web.archive.org/web/20100719104107/http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1544|archive-date=19 July 2010}}</ref>

On 26 July the heat reached near-record levels over [[Chad]] and [[Niger]].<ref name="wunderground.com">{{cite web |url=http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1516 |title=Wunder Blog : Weather Underground |publisher=Wunderground.com |access-date=28 July 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100627220406/http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1516 |archive-date=27 June 2010 }}</ref>