Editing Grass Valley, California (section)

==Geography==
Grass Valley is located at {{Coord|39|13|9|N|121|3|30|W|type:city}} (39.219215, -121.058414).<ref name="GR1">{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html|publisher=[[United States Census Bureau]]|access-date=April 23, 2011|date=February 12, 2011|title=US Gazetteer files: 2010, 2000, and 1990}}</ref> According to the [[United States Census Bureau]], the city has an area of {{convert|4.7|sqmi|km2}}, all of it land.

A variety of [[igneous]] and [[metamorphic]] rock supports Grass Valley. [[Granitic]] rock such as [[quartz diorite]] underlies the downtown core and extends south along Highway 49. Metavolcanic rock and [[diabase]] underlie areas around the granitic zone. Neighborhoods around Nevada County Golf Course and Sierra Nevada Memorial Hospital are underlain by [[ultramafic rock]]<ref>{{cite web|url=http://ngmdb.usgs.gov/Prodesc/proddesc_63087.htm|title=NGMDB Product Description Page|website=ngmdb.usgs.gov|access-date=August 12, 2017}}</ref> which supports infertile soils of the [[Dubakella (Soil)|Dubakella]] series. Here the vegetation is sparse considering the high average annual precipitation, with much grassland, and forested areas are often dominated by several species of oaks and the crooked, thin-crowned [[Pinus sabiniana|gray pine]].<ref>https://www.google.ca/maps/@39.2258162,-121.0474607,3a,75y,291.18h,76.97t/data=!3m4!1e1!3m2!1sH_ppfDYbTkOzB_i11BCCzA!2e0!6m1!1e1 {{webarchive|url=https://web.archive.org/web/20170812134040/https://www.google.ca/maps/%4039.2258162%2C-121.0474607%2C3a%2C75y%2C291.18h%2C76.97t/data%3D%213m4%211e1%213m2%211sH_ppfDYbTkOzB_i11BCCzA%212e0%216m1%211e1|date=August 12, 2017}} Google Street View showing [[gray pine]]-studded grassland on [[Dubakella (Soil)|Dubakella soil]].</ref> Luxuriant forest dominated by straight, dense [[Pinus ponderosa|ponderosa pine]] inhabits the more fertile soils, which include Musick series on granitic rock and Sites series on mafic or metamorphic rock.<ref>{{cite web|url=http://casoilresource.lawr.ucdavis.edu/gmap/|title=SoilWeb: An Online Soil Survey Browser|website=casoilresource.lawr.ucdavis.edu|access-date=August 12, 2017}}</ref><ref>https://www.google.ca/maps/place/Grass+Valley,+CA,+USA/@39.214774,-121.072447,3a,75y,57.91h,89.67t/data=!3m4!1e1!3m2!1sv44gtXC4_1h3ZL5ciV-FQQ!2e0!4m2!3m1!1s0x809b703f5e27f1a9:0x63ba323ef37bb379 Ponderosa pine in an area dominated by Sites soil as seen in Google Street View</ref>

===Climate===
Grass Valley has a [[hot-summer Mediterranean climate]] ([[Köppen climate classification|Köppen]] Csa) with warm to hot, dry summers and wet, cool, rainy winters. Summer is very dry, but thunderstorms may occur. Rainfall averages over {{convert|50|in|mm}} per year, in extreme contrast with the semi-arid valley below, which average as low as {{convert|12|in|mm}} in some parts. The high rainfall also gives the area green vegetation typical of an oceanic climate. This contributes to a heavy fuel-loading of brush and grass, which dry out during the near-rainless summer, posing a wildfire hazard.

Winters are cool but rarely cold. There are at least one or more snow events per year, often in the late winter. Frequent and large disruptive winter storms occur some years, while other years may have little to no snow. Less marine influence means that snow tends to occur more irregularly than some communities at similar elevation nearby to the south, such as [[Pollock Pines, California|Pollock Pines]].

Over the course of a year, 36.4 days of {{convert|90|°F}} or hotter and 0.9 days of {{convert|100|°F}} or hotter occur, with 61.4 days with minimum of {{convert|32|°F}} or colder.<ref name = NOAA/>

{{Weather box
|location = Grass Valley, California, 1991–2020 normals, extremes 1966–present
|single line = Yes

|Jan record high F = 77
|Feb record high F = 81
|Mar record high F = 82
|Apr record high F = 88
|May record high F = 99
|Jun record high F = 102
|Jul record high F = 108
|Aug record high F = 108
|Sep record high F = 108
|Oct record high F = 97
|Nov record high F = 87
|Dec record high F = 80

|Jan avg record high F = 67.0
|Feb avg record high F = 69.1
|Mar avg record high F = 72.6
|Apr avg record high F = 79.0
|May avg record high F = 85.8
|Jun avg record high F = 93.9
|Jul avg record high F = 97.8
|Aug avg record high F = 96.9
|Sep avg record high F = 93.9
|Oct avg record high F = 85.9
|Nov avg record high F = 75.3
|Dec avg record high F = 66.3
|year avg record high F = 99.8

|Jan high F = 53.6
|Feb high F = 54.9
|Mar high F = 57.9
|Apr high F = 62.7
|May high F = 70.8
|Jun high F = 80.2
|Jul high F = 88.0
|Aug high F = 87.4
|Sep high F = 82.3
|Oct high F = 72.1
|Nov high F = 59.8
|Dec high F = 52.6
|year high F =

|Jan mean F = 43.4
|Feb mean F = 44.5
|Mar mean F = 47.5
|Apr mean F = 51.3
|May mean F = 58.8
|Jun mean F = 66.4
|Jul mean F = 73.1
|Aug mean F = 72.1
|Sep mean F = 67.2
|Oct mean F = 58.2
|Nov mean F = 48.4
|Dec mean F = 42.6
|year mean F =

|Jan low F = 33.1
|Feb low F = 34.2
|Mar low F = 37.0
|Apr low F = 40.0
|May low F = 46.8
|Jun low F = 52.6
|Jul low F = 58.2
|Aug low F = 56.8
|Sep low F = 52.1
|Oct low F = 44.2
|Nov low F = 37.1
|Dec low F = 32.6
|year low F =

|Jan avg record low F = 24.4
|Feb avg record low F = 26.0
|Mar avg record low F = 28.1
|Apr avg record low F = 30.4
|May avg record low F = 36.9
|Jun avg record low F = 43.3
|Jul avg record low F = 50.8
|Aug avg record low F = 50.3
|Sep avg record low F = 43.7
|Oct avg record low F = 34.9
|Nov avg record low F = 28.0
|Dec avg record low F = 23.7
|year avg record low F = 21.7

|Jan record low F = 15
|Feb record low F = 9
|Mar record low F = 19
|Apr record low F = 26
|May record low F = 27
|Jun record low F = 36
|Jul record low F = 40
|Aug record low F = 41
|Sep record low F = 35
|Oct record low F = 27
|Nov record low F = 19
|Dec record low F = 3

|precipitation colour = green
|Jan precipitation inch = 9.30
|Feb precipitation inch = 8.98
|Mar precipitation inch = 8.16
|Apr precipitation inch = 4.43
|May precipitation inch = 2.48
|Jun precipitation inch = 0.74
|Jul precipitation inch = 0.00
|Aug precipitation inch = 0.11
|Sep precipitation inch = 0.44
|Oct precipitation inch = 2.56
|Nov precipitation inch = 5.52
|Dec precipitation inch = 10.48
|year precipitation inch = 53.20

|unit precipitation days = 0.01 in
|Jan precipitation days = 12.8
|Feb precipitation days = 11.7
|Mar precipitation days = 12.2
|Apr precipitation days = 8.5
|May precipitation days = 5.9
|Jun precipitation days = 2.7
|Jul precipitation days = 0.2
|Aug precipitation days = 0.8
|Sep precipitation days = 1.6
|Oct precipitation days = 4.4
|Nov precipitation days = 8.4
|Dec precipitation days = 12.3

|Jan snow inch = 0.7
|Feb snow inch = 3.0
|Mar snow inch = 3.0
|Apr snow inch = 0.5
|May snow inch = 0.0
|Jun snow inch = 0.0
|Jul snow inch = 0.0
|Aug snow inch = 0.0
|Sep snow inch = 0.0
|Oct snow inch = 0.0
|Nov snow inch = 0.2
|Dec snow inch = 1.2
|year snow inch =

|unit snow days = 0.1 in
|Jan snow days = 0.3
|Feb snow days = 1.0
|Mar snow days = 1.0
|Apr snow days = 0.3
|May snow days = 0.0
|Jun snow days = 0.0
|Jul snow days = 0.0
|Aug snow days = 0.0
|Sep snow days = 0.0
|Oct snow days = 0.0
|Nov snow days = 0.1
|Dec snow days = 0.3
|year snow days = 3.0

|source 1 = NOAA<ref name = NOAA>
{{cite web
|url = https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&stations=USC00043573&format=pdf&dataTypes=MLY-TMAX-NORMAL,MLY-TMIN-NORMAL,MLY-TAVG-NORMAL,MLY-PRCP-NORMAL,MLY-SNOW-NORMAL
|publisher = National Oceanic and Atmospheric Administration
|title = U.S. Climate Normals Quick Access – Station: Grass Valley #2, CA
|access-date = May 8, 2023
}}
</ref>
|source 2 = National Weather Service<ref name = NOWData>
{{cite web
|url = https://www.weather.gov/wrh/climate?wfo=sto
|publisher = National Weather Service
|title = NOAA Online Weather Data – NWS Sacramento
|access-date = May 8, 2023
}}
</ref>
}}