What is the hottest month in Monmouth?

July is the warmest month in Monmouth, with an average high of 84.1°F.

What is the coldest month in Monmouth?

January is the coldest month in Monmouth, with an average low of 14.7°F.

What month does Monmouth get the most rain?

May is typically the wettest month in Monmouth, with about 5.18 inches of precipitation.

What plant hardiness zone is Monmouth in?

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

Has the climate in Monmouth changed recently?

9.3% of Monmouth'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.

Monmouth, IL

Climate overview — based on NOAA 1991-2020 normals from MONMOUTH, IL US.

Dfa Hot-summer humid continental climate 6b USDA hardiness Zone 6b

Year-round temperatures (°F)

Avg high Avg low

Climate summary

Monmouth has an annual average temperature of 50.6°F with about 39.4 inches of precipitation per year and 25.6 inches of snow. The warmest month is July (average high 84.1°F), and the coldest is January (average low 14.7°F). May is typically the wettest month (5.18 in) and January the driest (1.85 in). Snow typically falls from October through April.

Pleasant months

2 / 12

avg high 65–80°F, low ≥ 50°F

Annual swing

50.7°F

warmest to coldest month

Heating need

5,844

HDD/yr

Cooling need

666

CDD/yr

Best time to visit Monmouth

Full guide →

Climate change signal

All-time records →

34 of 366 (9.3%) of Monmouth'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		29
1900s		30
1910s		52
1920s		23
1930s		61
1940s		17
1950s		27
1960s		14
1970s		12
1980s		22
1990s		16
2000s		18
2010s		27
2020s		18

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	31.4°F	14.7°F	23.1°F	1.85 in	8.7 in	7
February	36.2°F	18.7°F	27.5°F	1.98 in	6.1 in	7
March	49.7°F	29.1°F	39.4°F	2.61 in	3.3 in	8
April	62.8°F	39.7°F	51.3°F	3.95 in	1.1 in	10
May	72.9°F	50.9°F	61.9°F	5.18 in	—	12
June	81.2°F	60.3°F	70.8°F	4.53 in	—	10
July	84.1°F	63.6°F	73.8°F	3.96 in	—	8
August	82.8°F	61.5°F	72.2°F	3.92 in	—	8
September	77.3°F	53.6°F	65.4°F	3.70 in	—	7
October	64.8°F	42.2°F	53.5°F	3.01 in	0.2 in	8
November	49.2°F	30.6°F	39.9°F	2.58 in	1.4 in	7
December	36.5°F	20.8°F	28.6°F	2.15 in	4.8 in	7