Delta weather by month
What a typical year looks like in Delta, Iowa: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Sigourney, 9 km from Delta; records cover 1896–2026.
The year at a glance
- Precipitation a year
- 37.4 in950 mm
- Snow a year
- Rare
- Last spring freeze
- Apr 19
- First fall freeze
- Oct 15
- Heating degree days
- 6,642
- Cooling degree days
- 805
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −9°−23° (heating, 99%) and 94°34° (cooling, 1%).
Month by month
Delta in January
Highs average 30°−1° and lows 12°−11°, with 1.2 in30 mm of precipitation in a typical January.
- Record high
- 70°21° (1989)
- Record low
- −32°−36° (2019)
- Heating degree days
- 1375
- Cooling degree days
- 0
Delta in February
Highs average 35°1° and lows 15°−9°, with 1.5 in37 mm of precipitation in a typical February.
- Record high
- 77°25° (1930)
- Record low
- −30°−34° (1905)
- Heating degree days
- 1124
- Cooling degree days
- 0
Delta in March
Highs average 48°9° and lows 26°−3°, with 2.3 in59 mm of precipitation in a typical March.
- Record high
- 91°33° (2026)
- Record low
- −20°−29° (1962)
- Heating degree days
- 871
- Cooling degree days
- 1
Delta in April
Highs average 61°16° and lows 37°3°, with 3.7 in94 mm of precipitation in a typical April.
- Record high
- 93°34° (1965)
- Record low
- 7°−14° (1982)
- Heating degree days
- 486
- Cooling degree days
- 5
Delta in May
Highs average 71°22° and lows 49°10°, with 5 in126 mm of precipitation in a typical May.
- Record high
- 106°41° (1934)
- Record low
- 24°−4° (1907)
- Heating degree days
- 199
- Cooling degree days
- 45
Delta in June
Highs average 81°27° and lows 59°15°, with 5.1 in130 mm of precipitation in a typical June.
- Record high
- 105°41° (1934)
- Record low
- 35°2° (1903)
- Heating degree days
- 27
- Cooling degree days
- 172
Delta in July
Highs average 85°29° and lows 63°17°, with 3.9 in100 mm of precipitation in a typical July.
- Record high
- 113°45° (1901)
- Record low
- 45°7° (1899)
- Heating degree days
- 3
- Cooling degree days
- 272
Delta in August
Highs average 83°28° and lows 60°16°, with 4.8 in121 mm of precipitation in a typical August.
- Record high
- 111°44° (1934)
- Record low
- 39°4° (1915)
- Heating degree days
- 11
- Cooling degree days
- 215
Delta in September
Highs average 76°25° and lows 52°11°, with 3.5 in88 mm of precipitation in a typical September.
- Record high
- 103°39° (1899)
- Record low
- 16°−9° (1913)
- Heating degree days
- 114
- Cooling degree days
- 85
Delta in OctoberThis month
Highs average 63°17° and lows 40°4°, with 2.8 in71 mm of precipitation in a typical October.
- Record high
- 95°35° (1938)
- Record low
- 4°−16° (1925)
- Heating degree days
- 426
- Cooling degree days
- 10
Delta in November
Highs average 48°9° and lows 28°−2°, with 2.2 in55 mm of precipitation in a typical November.
- Record high
- 81°27° (1915)
- Record low
- −9°−23° (1898)
- Heating degree days
- 812
- Cooling degree days
- 0
Delta in December
Highs average 35°2° and lows 18°−8°, with 1.5 in39 mm of precipitation in a typical December.
- Record high
- 74°23° (2021)
- Record low
- −30°−34° (1924)
- Heating degree days
- 1194
- Cooling degree days
- 0