What is the hottest month in Marengo?

July is the warmest month in Marengo, with an average high of 84.0°F.

What is the coldest month in Marengo?

January is the coldest month in Marengo, with an average low of 10.4°F.

What month does Marengo get the most rain?

May is typically the wettest month in Marengo, with about 4.85 inches of precipitation.

What plant hardiness zone is Marengo in?

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

Has the climate in Marengo changed recently?

10.1% of Marengo'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.

Marengo, IA

Climate overview — based on NOAA 1991-2020 normals from WILLIAMSBURG 1E, IA US.

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

Year-round temperatures (°F)

Avg high Avg low

Climate summary

Marengo has an annual average temperature of 48.2°F with about 37.7 inches of precipitation per year and 28.1 inches of snow. The warmest month is July (average high 84.0°F), and the coldest is January (average low 10.4°F). May is typically the wettest month (4.85 in) and January the driest (1.16 in). Snow typically falls from October through April.

Pleasant months

1 / 12

avg high 65–80°F, low ≥ 50°F

Annual swing

53.9°F

warmest to coldest month

Heating need

6,618

HDD/yr

Cooling need

573

CDD/yr

Best time to visit Marengo

Full guide →

Climate change signal

All-time records →

37 of 366 (10.1%) of Marengo'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		0
1910s		10
1920s		25
1930s		119
1940s		24
1950s		27
1960s		20
1970s		12
1980s		27
1990s		20
2000s		32
2010s		26
2020s		24

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	28.4°F	10.4°F	19.4°F	1.16 in	7.6 in	6
February	33.0°F	14.3°F	23.7°F	1.46 in	7.7 in	6
March	46.5°F	25.8°F	36.1°F	2.19 in	3.6 in	8
April	60.4°F	36.4°F	48.4°F	3.92 in	0.9 in	10
May	71.3°F	48.9°F	60.1°F	4.85 in	0.1 in	12
June	80.5°F	59.4°F	69.9°F	4.80 in	—	11
July	84.0°F	62.6°F	73.3°F	4.32 in	—	9
August	82.1°F	59.7°F	70.9°F	4.47 in	—	9
September	76.3°F	50.7°F	63.5°F	3.80 in	—	8
October	63.0°F	38.6°F	50.8°F	2.83 in	0.3 in	8
November	47.3°F	26.9°F	37.1°F	2.20 in	1.6 in	7
December	34.2°F	16.3°F	25.3°F	1.69 in	6.3 in	7