What is the hottest month in Sumner, IA?

July is the warmest month, with a normal high of 83°F at Tripoli.

What is the coldest month in Sumner, IA?

January is the coldest month, with a normal low of 7°F.

What is the wettest month in Sumner, IA?

June has the most precipitation on average, about 6.03 inches.

Checked Oct 25, 2026

Sumner, IA Climate

1991 to 2020 normals at Tripoli, 8.5 mi from the center of Sumner, elevation 1055 ft.

Average weather by month

Select a month for daily normals and last year's weather

Month	High	Low	Precip.	Snow
January	25°	7°	1.23 in	--
February	29°	12°	1.09 in	--
March	43°	24°	2.00 in	--
April	58°	36°	3.93 in	--
May	70°	48°	5.11 in	--
June	80°	59°	6.03 in	--
July	83°	62°	4.80 in	--
August	81°	59°	4.29 in	--
September	75°	50°	3.75 in	--
October	61°	38°	2.96 in	--
November	44°	26°	1.98 in	--
December	31°	15°	1.47 in	--
Year	57°		38.64 in	--

Frequently asked questions

What is the hottest month in Sumner, IA?: July is the warmest month, with a normal high of 83°F at Tripoli.
What is the coldest month in Sumner, IA?: January is the coldest month, with a normal low of 7°F.
What is the wettest month in Sumner, IA?: June has the most precipitation on average, about 6.03 inches.

Today

Sumner, IA forecast

Data sources

U.S. Climate Normals 1991-2020NOAA National Centers for Environmental Information
U.S. Climate Normals 1991-2020 (daily) and GHCN-Daily via Access Data ServiceNOAA National Centers for Environmental Information

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About this data

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Climate normals are 30-year averages measured at one weather station, which may be miles from the place named here or at a different elevation.

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