Waterloo weather in May: Waterloo, Iowa: normal highs, lows, rain and records for May
Waterloo in May has a normal high of 73°F and a normal low of 50°F, a daily mean of 62°F, rising from 67°F on the 1st to 78°F by the 31st. Measurable precipitation falls on 13 days in a normal May, 4.61 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 23°C and low of 10°C, 117 mm of precipitation and 0 cm of snow in May.
- NOAA stationWaterloo Municipal Airport
- Station IDUSW00094910
- Location42.55°N 92.40°W
- Elevation868 ft (265 m)
- Population67,477
- Jan 28° 11°
- Feb 33° 15°
- Mar 47° 27°
- Apr 61° 38°
- May 73° 50°
- Jun 82° 61°
- Jul 85° 64°
- Aug 83° 61°
- Sep 77° 52°
- Oct 63° 40°
- Nov 47° 28°
- Dec 34° 17°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Waterloo in May?
The normal high is 73°F and the normal low 50°F, for a daily mean of 61.5°F. May is 12.1°F warmer than April and 10.0°F cooler than June. May is the 5th warmest month of the year in Waterloo and the 2nd wettest. Across the month the normal high rises 11°F, from 67°F on May 1 to 78°F on May 31. From one year to the next May's mean temperature typically moves about 2.9°F either way (NOAA's standard deviation), so roughly two Mays in three average between 59°F and 64°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 42%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| May 1 | 67°F | 44°F | 40% | 25% |
| May 8 | 70°F | 47°F | 41% | 26% |
| May 15 | 73°F | 50°F | 41% | 26% |
| May 22 | 75°F | 53°F | 42% | 27% |
| May 31 | 78°F | 56°F | 42% | 28% |
Every day of May: normal high, low and chance of precipitation (warmest afternoon May 31, coldest night May 1)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| May 1 | 67°F | 44°F | 40% | 25% | 14 h |
| May 2 | 68°F | 44°F | 40% | 25% | 14 h |
| May 3 | 68°F | 45°F | 40% | 26% | 14 h 10 min |
| May 4 | 68°F | 45°F | 41% | 26% | 14 h 10 min |
| May 5 | 69°F | 46°F | 41% | 26% | 14 h 10 min |
| May 6 | 69°F | 46°F | 41% | 26% | 14 h 10 min |
| May 7 | 69°F | 47°F | 41% | 26% | 14 h 20 min |
| May 8 | 70°F | 47°F | 41% | 26% | 14 h 20 min |
| May 9 | 70°F | 47°F | 41% | 26% | 14 h 20 min |
| May 10 | 71°F | 48°F | 41% | 26% | 14 h 20 min |
| May 11 | 71°F | 48°F | 41% | 26% | 14 h 30 min |
| May 12 | 71°F | 49°F | 41% | 26% | 14 h 30 min |
| May 13 | 72°F | 49°F | 41% | 26% | 14 h 30 min |
| May 14 | 72°F | 49°F | 41% | 26% | 14 h 30 min |
| May 15 | 73°F | 50°F | 41% | 26% | 14 h 30 min |
| May 16 | 73°F | 50°F | 41% | 26% | 14 h 40 min |
| May 17 | 73°F | 51°F | 41% | 26% | 14 h 40 min |
| May 18 | 74°F | 51°F | 41% | 26% | 14 h 40 min |
| May 19 | 74°F | 52°F | 41% | 26% | 14 h 40 min |
| May 20 | 74°F | 52°F | 41% | 26% | 14 h 40 min |
| May 21 | 75°F | 52°F | 41% | 27% | 14 h 50 min |
| May 22 | 75°F | 53°F | 42% | 27% | 14 h 50 min |
| May 23 | 76°F | 53°F | 42% | 27% | 14 h 50 min |
| May 24 | 76°F | 54°F | 42% | 27% | 14 h 50 min |
| May 25 | 76°F | 54°F | 42% | 27% | 14 h 50 min |
| May 26 | 77°F | 54°F | 42% | 27% | 15 h |
| May 27 | 77°F | 55°F | 42% | 27% | 15 h |
| May 28 | 77°F | 55°F | 42% | 28% | 15 h |
| May 29 | 78°F | 56°F | 42% | 28% | 15 h |
| May 30 | 78°F | 56°F | 42% | 28% | 15 h |
| May 31 | 78°F | 56°F | 42% | 28% | 15 h |
- Normal high
- 73°FMay average
- Normal low
- 50°FMay average
- Precipitation
- 4.61 inmonth total
- Days with precipitation
- 130.01 inch or more
- Snowfall
- 0.1 inmonth total
- Days at 90°F or more
- 1
- Nights at 32°F or colder
- 1
- Daylight
- 14 h to 15 hMay 1 to May 31
- Days at 70°F or more
- 18
- Days at 80°F or more
- 8
- Sunshine
- 71%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00094910; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain or snow in Waterloo in May?
On a given May day the chance of 0.01 inch or more is 41% on average, highest around May 25 (42%). In all, 4.61 in falls on 13 days of a normal May, 1 of them with an inch or more.
In a normal May in Waterloo, 1 days reach 90°F, 1 nights fall to freezing and snowfall averages 0.1 inches.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00094910.
How humid and windy is Waterloo in May?
At 3 p.m. the normal temperature is 74°F with 49% relative humidity and a dew point of 54°F; at 6 a.m. it is 58°F with 84% humidity. The wind averages 9.1 mph, most often from the south-southwest in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 58°F | 54°F | 84% | 7.1 mph | 58% |
| 9 a.m. | 67°F | 55°F | 65% | 10.5 mph | 62% |
| noon | 72°F | 54°F | 53% | 11.8 mph | 53% |
| 3 p.m. | 74°F | 54°F | 49% | 12.0 mph | 54% |
| 6 p.m. | 72°F | 53°F | 51% | 10.9 mph | 57% |
| 9 p.m. | 65°F | 54°F | 69% | 7.4 mph | 64% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094910. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for May in Waterloo?
The warmest May temperature on Waterloo's official record (since 1895) is 108°F, on May 31, 1934; the coldest is 22°F, on May 4, 1907. The wettest May brought 10.81 in (2013); the snowiest, 2.0 inches (1945).
The May mean against the 1991-2020 normal of 61.5°F: 2021 59.6°F (−1.9), 2022 62.2°F (+0.7), 2023 64.4°F (+2.9), 2024 62.8°F (+1.3), 2025 60.9°F (−0.6), 2026 60.9°F (−0.6). 3 of 6 ran warmer than normal.
| May | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 59.6°F | −1.9°F | 3.48 in |
| 2022 | 62.2°F | +0.7°F | 4.08 in |
| 2023 | 64.4°F | +2.9°F | 1.75 in |
| 2024 | 62.8°F | +1.3°F | 10.04 in |
| 2025 | 60.9°F | −0.6°F | 2.37 in |
| 2026 | 60.9°F | −0.6°F | 2.76 in |
Source: records: ACIS, NWS threaded record ALOthr; recent months: ACIS, station USW00094910. Records and recent months use complete months only.
How does May in Waterloo compare across Iowa?
Across the 132 places PlainClimate covers in Iowa, May normal highs run from 66°F in Northwood to 74°F in Glenwood; Waterloo's is 73°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.