Oconomowoc weather in May

In May, Oconomowoc sees average daytime highs of 68°F and overnight lows near 49°F, with 3.8 in of rain across 11.9 wet days and about 14.4 hours of daylight. It is the 5th-warmest and 3rd-wettest month of the year here.

Highs climb over the month, from about 63°F in the first days to 72°F by the end. The sky is clear or mostly clear about 24% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 54 min at the start of May to 14 h 54 min by month's end. Set against the rest of the year, May is Oconomowoc's 6th-clearest and 7th-windiest month. For the whole year in context, see Oconomowoc's year-round climate.

Daytime high
68°
5th warmest
Overnight low
49°
8th coldest
Rainfall
3.8 in
11.9 wet days
Daylight
14 h 30 min
4:36 AM – 7:04 PM
Cloud cover
65%
6th clearest
Wind
8 mph
7th windiest
Solar energy
5.74 kWh/m²
Travel score
5.9
out of 10

Oconomowoc is city in Waukesha County, Wisconsin, United States.

Founded
1837

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 63°F in the first days to 72°F by the end.

A typical May day in Oconomowoc reaches about 68°F in the afternoon and slips back to 49°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 55°F and 82°F. Set against its neighbours, May runs about 11°F warmer than April and about 10°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16244
26344
36344
46445
56445
66446
76546
86546
96547
106647
116647
126647
136748
146748
156748
166849
176849
186949
196950
206950
217051
227051
237051
247152
257152
267152
277253
287253
297353
307354
317354

How May really feels in Oconomowoc

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Oconomowoc weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan28° / 14°1.78.26.89.20.0
Feb32° / 17°1.775.710.20.0
Mar44° / 27°2.39.44.111.60.9
Apr56° / 38°3.911.91.613.13.7
May68° / 49°3.811.9014.45.9
Jun78° / 59°3.811.4015.16.5
Jul81° / 64°3.49.7014.96.5
Aug79° / 62°3.510.3013.86.7
Sep72° / 54°2.98.5012.36.9
Oct59° / 42°2.890.310.84.7
Nov45° / 31°2.18.229.51.0
Dec33° / 20°2.07.75.18.90.0

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 17% of May, with mostly cloudy or overcast conditions the remaining 59%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13862
23862
33862
43862
53862
63862
73862
83961
93961
103961
113961
124060
134060
144060
154060
164159
174159
184159
194159
204258
214258
224258
234258
244258
254357
264357
274357
284357
294456
304456
314456

Chance of precipitation in May

Any precipitation

Oconomowoc gets around 3.8 in of rain over 11.9 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 38% and peaks near 39% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
138
238
338
439
539
639
739
839
939
1039
1139
1239
1339
1438
1538
1638
1738
1838
1938
2037
2137
2237
2338
2438
2538
2638
2739
2839
2939
3039
3139

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 82% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
195410
294510
393520
493520
593520
691630
791630
890640
990640
1089650
1188750
1287751
1387751
1485861
1585861
1685861
1782972
1882972
1981973
2080983
21781084
22771094
23751195
247411105
257312105
267213105
277013116
286914116
296715126
306715126
316616126

Wind in May

Winds average 8 mph in May.

Across May, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
277light breeze
287light breeze
297calm
307calm
317calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 54 min at the start of May to 14 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over May. Sunrise moves from 4:55 AM to 4:24 AM, and sunset from 6:47 PM to 7:19 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.94:556:47
213.94:546:48
314.04:526:50
414.04:516:51
514.04:506:52
614.14:486:53
714.14:476:54
814.24:466:55
914.24:446:56
1014.24:436:58
1114.34:426:59
1214.34:417:00
1314.44:407:01
1414.44:387:02
1514.44:377:03
1614.54:367:04
1714.54:357:05
1814.54:347:06
1914.64:337:07
2014.64:327:08
2114.64:317:09
2214.74:307:11
2314.74:307:12
2414.74:297:12
2514.84:287:13
2614.84:277:14
2714.84:267:15
2814.84:267:16
2914.94:257:17
3014.94:247:18
3114.94:247:19

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.74 kWh/m².

For context, solar energy here swings from a low near 1.55 kWh/m² to a high of 6.29 kWh/m² in June across the year — May's 5.74 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.4Bright
45.4Bright
55.4Bright
65.4Bright
75.5Bright
85.5Bright
95.5Bright
105.5Bright
115.6Bright
125.6Bright
135.7Bright
145.7Bright
155.7Bright
165.8Bright
175.8Bright
185.8Bright
195.9Bright
205.9Bright
215.9Bright
225.9Bright
236.0Bright
246.0Bright
256.0Bright
266.0Intense
276.0Intense
286.0Intense
296.0Intense
306.1Intense
316.1Intense
Planning a trip in May

Is May a good time to visit Oconomowoc?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.9
Sightseeing
5th-best month of the year
3.1
Beach & pool
5th-best month of the year

May is a reasonable time to visit Oconomowoc for sightseeing.

What to pack for Oconomowoc in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Oconomowoc sees daytime highs around 68°F and nights near 49°F. Worth packing: rain gear and sun protection. About 12 days see rain.

rain gearsun protection

Sea temperature near Oconomowoc in May

The nearest coast averages about 42°F in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 32 mi away) is warmest in August at about 70°F and coldest in March near 36°F.

It's comfortable for a long swim from Jul 29 to Aug 30 — about 1.1 months when the water holds above 68°F.

30°40°50°60°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarm
Sea temperature (°F)Comfort
Jan38Bracing
Feb36Bracing
Mar36Bracing
Apr38Bracing
May42Bracing
Jun54Bracing
Jul67Cool
Aug70Refreshing
Sep66Cool
Oct56Bracing
Nov46Bracing
Dec41Bracing

UV index in Oconomowoc in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Oconomowoc peaks around June 20 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 20UV 9Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Oconomowoc in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in Oconomowoc is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (October, 9 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodJul 1616 µg/m³Oct 239 µg/m³
PM2.5 (µg/m³)Level
Jan12Good
Feb14Moderate
Mar15Moderate
Apr13Moderate
May15Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep12Moderate
Oct9Good
Nov9Good
Dec10Good
Location & terrain

Where is Oconomowoc?

Oconomowoc sits at 43.1°N, 88.5°W, 863 ft above sea level, in United States. The nearest listed city is Watertown, 13 mi away.

Topography around Oconomowoc

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Oconomowoc.

Within 2 miles, the terrain around Oconomowoc has only modest variations in elevation — a maximum elevation change of 148 ft around an average of 879 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 440 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 846 ft.

The land around Oconomowoc is covered by trees (35%), grassland (23%) and artificial surfaces (20%) within 2 miles, trees (36%), cropland (31%) and grassland (24%) within 10 miles, and cropland (44%) and trees (23%) within 50 miles.

2 miles
148 ft
10 miles
440 ft
50 miles
846 ft
treesgrasslandcroplandartificial surfaceswaterwetland
May weather nearby: Watertown 13 mi · Waukesha 15 mi · Menomonee Falls 20 mi · Brookfield 20 mi · Germantown 21 mi · New Berlin 22 mi · Muskego 23 mi · Mequon 25 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Oconomowoc (43.1117°, -88.4993°, elevation 863 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).