Editing Altadena, California (section)

=== Climate ===
Altadena experiences hot and dry summers that are followed by warm and windy falls and mild winters. According to the [[Köppen climate classification]] system, Altadena has a [[Mediterranean climate#Hot-summer Mediterranean climate|hot-summer Mediterranean climate]], abbreviated ''Csa'' on climate maps. {{Weather box|location = Altadena, California (1991-2020 averages, 1922-2016 extremes)
|single line = Y
|Jan record high F =  93
|Feb record high F =  92
|Mar record high F =  98
|Apr record high F = 105
|May record high F = 104
|Jun record high F = 113
|Jul record high F = 110
|Aug record high F = 107
|Sep record high F = 111
|Oct record high F = 108
|Nov record high F = 101
|Dec record high F =  93
|year record high F = 113
|Jan high F = 64.3
|Feb high F = 64.4
|Mar high F = 66.6
|Apr high F = 67.0
|May high F = 75.0
|Jun high F = 79.1
|Jul high F = 85.8
|Aug high F = 86.8
|Sep high F = 84.6
|Oct high F = 76.9
|Nov high F = 72.8
|Dec high F = 65.8
|year high F = 
|Jan low F = 42.3
|Feb low F = 43.9
|Mar low F = 44.8
|Apr low F = 45.9
|May low F = 50.2
|Jun low F = 52.9
|Jul low F = 57.7
|Aug low F = 59.1
|Sep low F = 58.4
|Oct low F = 51.8
|Nov low F = 48.5
|Dec low F = 44.6
|year low F = 
|Jan record low F = 21
|Feb record low F = 26
|Mar record low F = 29
|Apr record low F = 31
|May record low F = 32
|Jun record low F = 41
|Jul record low F = 45
|Aug record low F = 43
|Sep record low F = 41
|Oct record low F = 36
|Nov record low F = 26
|Dec record low F = 25
|year record low F = 21
|rain colour = green
|Jan rain inch = 4.80
|Feb rain inch = 5.74
|Mar rain inch = 3.19
|Apr rain inch = 1.29
|May rain inch = 0.74
|Jun rain inch = 0.21
|Jul rain inch = 0.08
|Aug rain inch = 0.01
|Sep rain inch = 0.18
|Oct rain inch = 0.91
|Nov rain inch = 1.18
|Dec rain inch = 3.04
|year rain inch = 
|Jan rain days = 6.4
|Feb rain days = 6.0
|Mar rain days = 4.9
|Apr rain days = 2.9
|May rain days = 2.4
|Jun rain days = 0.8
|Jul rain days = 0.2
|Aug rain days = 0.2
|Sep rain days = 0.7
|Oct rain days = 2.4
|Nov rain days = 2.4
|Dec rain days = 4.9
|unit rain days = 0.01 inch
|source 1 = WRCC<ref>{{cite web
|url=https://climateatlas.org/php/viewstation.php?station=USC00040144 |title=ALTADENA, CALIFORNIA - Climate Summary|access-date=March 21, 2022|publisher=WRCC}}</ref>
|source 2 = WRCC<ref>{{cite web
|url=https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0144 |title=ALTADENA, CALIFORNIA - Climate Summary|access-date=October 3, 2017|publisher=WRCC}}</ref>
|date=October 2017
}}

The wettest calendar year was 1983, with {{convert|48.47|in|mm|1}}, and the driest was 1947, with {{convert|5.37|in|mm|1}}. The most rainfall in one month was {{convert|19.70|in|mm|1}}, in February 1980. The most rainfall in 24 hours was {{convert|7.70|in|mm|1}}, on March 2, 1938. Altadena averages {{convert|21.09|in|mm|1}} of rain a year, over {{convert|6|inch|mm|-1}} more than nearby Los Angeles due to the [[Precipitation types#Orographic|orographic]] effect created by the [[San Gabriel Mountains]]. Because of the slope on which the city is built, sewer lines in the city's northern section have been known to overflow significantly.{{Citation needed|date=December 2013}}