What is the hottest month in New Castle?

July is the warmest month in New Castle, with an average high of 88.6°F.

What is the coldest month in New Castle?

January is the coldest month in New Castle, with an average low of 12.3°F.

What month does New Castle get the most rain?

May is typically the wettest month in New Castle, with about 1.69 inches of precipitation.

What plant hardiness zone is New Castle in?

New Castle is approximately in USDA plant hardiness Zone 6b, based on the average annual extreme minimum temperature.

Has the climate in New Castle changed recently?

10.7% of New Castle's all-time daily heat records were set in the last decade (since 2015), compared to roughly 5% if records were evenly distributed over time.

New Castle, CO

Climate overview — based on NOAA 1991-2020 normals from GLENWOOD SPGS #2, CO US.

Dfb Warm-summer humid continental climate 6b USDA hardiness Zone 6b

Year-round temperatures (°F)

Avg high Avg low

Climate summary

New Castle has an annual average temperature of 47.6°F with about 15.5 inches of precipitation per year and 38.9 inches of snow. The warmest month is July (average high 88.6°F), and the coldest is January (average low 12.3°F). May is typically the wettest month (1.69 in) and June the driest (0.96 in). Snow typically falls from October through April.

Annual swing

46.7°F

warmest to coldest month

Heating need

6,555

HDD/yr

Cooling need

300

CDD/yr

Best time to visit New Castle

Full guide →

Climate change signal

All-time records →

39 of 366 (10.7%) of New Castle'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.

1890s		2
1900s		4
1910s		13
1920s		25
1930s		38
1940s		63
1950s		34
1960s		16
1970s		18
1980s		32
1990s		34
2000s		34
2010s		36
2020s		17

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	36.2°F	12.3°F	24.3°F	1.13 in	13.7 in	8
February	41.6°F	19.0°F	30.3°F	1.16 in	6.3 in	6
March	53.0°F	26.1°F	39.5°F	1.18 in	2.4 in	6
April	60.0°F	32.0°F	46.0°F	1.63 in	0.6 in	7
May	70.6°F	39.6°F	55.1°F	1.69 in	—	6
June	82.4°F	46.3°F	64.3°F	0.96 in	—	5
July	88.6°F	53.4°F	71.0°F	1.07 in	—	5
August	86.0°F	52.1°F	69.0°F	1.27 in	—	7
September	78.2°F	43.8°F	61.0°F	1.63 in	—	6
October	64.8°F	33.3°F	49.0°F	1.56 in	0.7 in	6
November	49.1°F	23.6°F	36.3°F	1.06 in	4.4 in	6
December	36.4°F	15.1°F	25.7°F	1.19 in	10.8 in	7