Joliet weather in May

In May, Joliet sees average daytime highs of 70°F and overnight lows near 52°F, with 4.6 in of rain across 12.5 wet days and about 14.3 hours of daylight. It is the 5th-warmest and 1st-wettest month of the year here.

Highs climb over the month, from about 66°F in the first days to 74°F by the end. The sky is clear or mostly clear about 26% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of May to 14 h 48 min by month's end. Set against the rest of the year, May is Joliet's 6th-clearest and 8th-windiest month. For the whole year in context, see Joliet's year-round climate.

Daytime high
70°
5th warmest
Overnight low
52°
8th coldest
Rainfall
4.6 in
12.5 wet days
Daylight
14 h 18 min
4:39 AM – 6:58 PM
Cloud cover
64%
6th clearest
Wind
8 mph
8th windiest
Solar energy
5.8 kWh/m²
Travel score
6.1
out of 10

Joliet is city in Illinois, United States.

Density
909/km²
people per km²
Founded
1833

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 66°F in the first days to 74°F by the end.

A typical May day in Joliet reaches about 70°F in the afternoon and slips back to 52°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 57°F and 83°F. Set against its neighbours, May runs about 10°F warmer than April and about 9°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16546
26547
36647
46647
56648
66748
76749
86749
96849
106850
116950
126950
136951
146951
157051
167051
177052
187152
197152
207153
217253
227253
237354
247354
257355
267355
277455
287456
297456
307556
317557

How May really feels in Joliet

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.

Joliet weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan32° / 18°2.38.65.59.30.0
Feb36° / 21°2.07.14.610.30.0
Mar47° / 31°2.810.22.811.71.6
Apr60° / 41°4.412.40.713.14.4
May70° / 52°4.612.5014.36.1
Jun80° / 62°4.311.7014.96.3
Jul83° / 66°3.711.4014.75.7
Aug81° / 64°3.710.2013.76.5
Sep75° / 56°2.98.3012.37.1
Oct62° / 44°3.29.20.110.95.5
Nov48° / 33°2.78.61.29.71.9
Dec37° / 24°2.28.33.890.0

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% 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
83862
93862
103862
113961
124060
134060
144060
154159
164159
174258
184258
194258
204258
214357
224357
234357
244456
254456
264456
274456
284456
294456
304555
314555

Chance of precipitation in May

Any precipitation

Joliet gets around 4.6 in of rain over 12.5 wet days in May, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 41% and peaks near 42% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
142
242
342
442
542
642
742
842
941
1041
1141
1241
1341
1441
1541
1640
1740
1840
1940
2040
2140
2240
2340
2440
2540
2640
2740
2840
2940
3040
3140

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 70% of days. Sticky, muggy-or-worse air turns up on roughly 6% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
18710210
28611210
38611210
48412310
58213320
68113420
78113420
87814530
97814530
107714630
117515640
127415740
137315840
147315840
157115950
167115950
1770151050
1869151060
1968151160
2067151170
2166151270
2264151380
2363161380
2461161490
2561161490
26581715100
27571715101
28561715111
29541816111
30531816121
31521916121

Wind in May

Winds average 8 mph in May.

Across May, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light 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
278light breeze
288light breeze
298light breeze
308light breeze
318light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 48 min at the start of May to 14 h 48 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 4:57 AM to 4:27 AM, and sunset from 6:42 PM to 7:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.84:576:42
213.84:556:44
313.84:546:45
413.94:536:46
513.94:516:47
614.04:506:48
714.04:496:49
814.04:486:50
914.14:466:51
1014.14:456:52
1114.24:446:53
1214.24:436:54
1314.24:426:55
1414.34:416:56
1514.34:406:57
1614.34:396:58
1714.44:386:59
1814.44:377:00
1914.44:367:01
2014.54:357:02
2114.54:347:03
2214.54:337:04
2314.54:327:05
2414.64:327:06
2514.64:317:07
2614.64:307:08
2714.74:307:09
2814.74:297:10
2914.74:287:11
3014.74:287:11
3114.84:277:12

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.8 kWh/m².

For context, solar energy here swings from a low near 1.67 kWh/m² to a high of 6.4 kWh/m² in June across the year — May's 5.8 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.4Bright
25.4Bright
35.4Bright
45.5Bright
55.5Bright
65.5Bright
75.5Bright
85.6Bright
95.6Bright
105.6Bright
115.7Bright
125.7Bright
135.7Bright
145.8Bright
155.8Bright
165.8Bright
175.8Bright
185.9Bright
195.9Bright
205.9Bright
215.9Bright
226.0Bright
236.0Bright
246.0Bright
256.0Intense
266.0Intense
276.0Intense
286.1Intense
296.1Intense
306.1Intense
316.1Intense
Planning a trip in May

Is May a good time to visit Joliet?

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

6.1
Sightseeing
4th-best month of the year
3.8
Beach & pool
5th-best month of the year

May is a reasonable time to visit Joliet for sightseeing.

What to pack for Joliet in May

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

In May, Joliet sees daytime highs around 70°F and nights near 52°F. Worth packing: rain gear and sun protection. About 13 days see rain.

rain gearsun protection

Sea temperature near Joliet in May

The nearest coast averages about 45°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 34 mi away) is warmest in August at about 73°F and coldest in February near 36°F.

It's comfortable for a long swim from Jul 13 to Sep 15 — about 2.1 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°F)Comfort
Jan38Bracing
Feb36Bracing
Mar36Bracing
Apr39Bracing
May45Bracing
Jun57Bracing
Jul70Refreshing
Aug73Refreshing
Sep68Refreshing
Oct58Bracing
Nov49Bracing
Dec42Bracing

UV index in Joliet in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Joliet peaks around June 22 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 2 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 22UV 9Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec2Low

Air quality in Joliet 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 Joliet is worst in July — around 18 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1418 µg/m³Oct 238 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar15Moderate
Apr15Moderate
May17Moderate
Jun17Moderate
Jul18Moderate
Aug16Moderate
Sep12Moderate
Oct8Good
Nov9Good
Dec10Good
Location & terrain

Where is Joliet?

Joliet sits at 41.5°N, 88.1°W, 541 ft above sea level, in United States. The nearest listed city is Crest Hill, 2.5 mi away.

Topography around Joliet

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

Within 2 miles, the terrain around Joliet has only modest variations in elevation — a maximum elevation change of 243 ft around an average of 594 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 404 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 751 ft.

The land around Joliet is covered by artificial surfaces (50%) and trees (36%) within 2 miles, grassland (26%), trees (25%) and cropland (25%) within 10 miles, and cropland (51%) within 50 miles.

2 miles
243 ft
10 miles
404 ft
50 miles
751 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Crest Hill 2.5 mi · Lockport 4.3 mi · Shorewood 6.2 mi · New Lenox 6.2 mi · Romeoville 8.7 mi · Homer Glen 9.3 mi · Plainfield 9.3 mi · Mokena 9.9 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 Joliet (41.5252°, -88.0834°, elevation 541 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).