Union City, CA

Climate overview — based on NOAA 1991-2020 normals from FREMONT, CA US.

BSk Semi-arid (cold) climate 9b USDA hardiness Zone 9b

Year-round temperatures (°F)

40° 50° 60° 70° 80° J F M A M J J A S O N D
Avg high Avg low

Climate summary

Union City has an annual average temperature of 59.5°F with about 15.9 inches of precipitation per year. The warmest month is September (average high 78.3°F), and the coldest is December (average low 42.5°F). February is typically the wettest month (3.17 in) and July the driest (0.00 in).

Pleasant months
6 / 12
avg high 65–80°F, low ≥ 50°F
Annual swing
17.2°F
warmest to coldest month
Heating need
2,181
Cooling need
216

Best time to visit Union City

Full guide →

Climate change signal

All-time records →

133 of 366 (36.3%) of Union City's all-time daily heat records have been set since 2015. If records were spread evenly across the station's history, only about 5% would fall in any given decade.

1990s
64
2000s
116
2010s
122
2020s
64

Bars: number of all-time daily heat records still standing that were set in each decade.

Monthly averages

Month Avg High Avg Low Avg Temp Precipitation Snow Rainy days
January 58.6°F 42.6°F 50.6°F 3.00 in 10
February 61.4°F 44.4°F 52.9°F 3.17 in 10
March 65.1°F 46.4°F 55.8°F 2.52 in 10
April 67.7°F 48.3°F 58.0°F 1.22 in 6
May 71.1°F 51.9°F 61.5°F 0.50 in 3
June 75.3°F 54.7°F 65.0°F 0.16 in 1
July 77.9°F 56.8°F 67.3°F 0.00 in 0
August 78.2°F 57.1°F 67.7°F 0.02 in 0
September 78.3°F 56.0°F 67.2°F 0.10 in 1
October 73.3°F 52.0°F 62.6°F 0.69 in 3
November 64.6°F 46.2°F 55.4°F 1.59 in 7
December 58.4°F 42.5°F 50.5°F 2.97 in 10

Climate twins of Union City

Why these? →

The most climatically similar US cities at least 140 miles away (by monthly temperature + precipitation pattern).

Frost dates
Last spring / first fall frost
All-time records
Hottest, coldest, wettest
Planting calendar
What to plant, and when

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