Jacksonville weather in May

In May, Jacksonville sees average daytime highs of 74°F and overnight lows near 55°F, with 4.4 in of rain across 13.4 wet days and about 14.2 hours of daylight. It is the 5th-warmest and 2nd-wettest month of the year here.

Highs climb over the month, from about 69°F in the first days to 78°F by the end. The sky is clear or mostly clear about 27% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 42 min at the start of May to 14 h 36 min by month's end. Set against the rest of the year, May is Jacksonville's 8th-clearest and 8th-windiest month. For the whole year in context, see Jacksonville's year-round climate.

Daytime high
74°
5th warmest
Overnight low
55°
8th coldest
Rainfall
4.4 in
13.4 wet days
Daylight
14 h 12 min
4:52 AM – 7:03 PM
Cloud cover
63%
8th clearest
Wind
8 mph
8th windiest
Solar energy
5.79 kWh/m²
Travel score
6.2
out of 10

Jacksonville is city in Morgan County, Illinois, United States.

Density
691/km²
people per km²
Founded
1825

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 69°F in the first days to 78°F by the end.

A typical May day in Jacksonville reaches about 74°F in the afternoon and slips back to 55°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 61°F and 85°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)
16950
26950
36951
47051
57052
67152
77153
87153
97253
107253
117254
127354
137354
147355
157355
167455
177456
187456
197456
207557
217557
227657
237658
247658
257658
267759
277759
287760
297860
307860
317860

How May really feels in Jacksonville

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.

Jacksonville weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan36° / 21°2.37.749.50.0
Feb41° / 24°2.27.23.410.40.3
Mar52° / 34°3.110.31.611.72.8
Apr64° / 45°4.611.50.4135.4
May74° / 55°4.413.4014.26.2
Jun82° / 65°4.111.1014.85.8
Jul85° / 68°3.39.5014.55.3
Aug84° / 66°3.09013.65.7
Sep78° / 58°2.97.5012.37.3
Oct66° / 46°3.08.30.110.96.3
Nov52° / 35°3.28.20.99.82.8
Dec40° / 26°2.37.42.79.20.2

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 27% 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 58%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13961
23961
33961
43961
53961
64060
74060
84060
94159
104159
114258
124258
134258
144258
154357
164357
174357
184258
194258
204258
214258
224357
234258
244357
254357
264357
274456
284456
294555
304555
314555

Chance of precipitation in May

Any precipitation

Jacksonville gets around 4.4 in of rain over 13.4 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 43% and peaks near 44% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
144
244
344
444
544
644
743
843
943
1043
1142
1242
1342
1442
1542
1642
1742
1842
1943
2043
2143
2243
2343
2443
2543
2643
2743
2843
2942
3042
3141

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 55% of days. Sticky, muggy-or-worse air turns up on roughly 11% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
17615720
27416820
37217920
470171030
569171130
666181240
765181340
863181450
964171450
1062171560
1160171670
1259171770
1359161780
1458161880
1557161890
1656161990
17561519100
18541520110
19521520121
20521520121
21501521131
22491621141
23471621151
24461621161
25441721171
26431721181
27421721191
28401821191
29391921201
30381920212
31362020222

Wind in May

Winds average 8 mph in May.

Across May, daily wind ranges from about 7 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
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
278light breeze
288light breeze
298light breeze
307light breeze
317light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 42 min at the start of May to 14 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 54 minutes over May. Sunrise moves from 5:08 AM to 4:41 AM, and sunset from 6:48 PM to 7:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.75:086:48
213.75:076:49
313.75:066:50
413.85:056:51
513.85:036:52
613.85:026:53
713.95:016:54
813.95:006:55
913.94:596:56
1014.04:586:57
1114.04:576:58
1214.14:566:59
1314.14:557:00
1414.14:547:01
1514.24:537:02
1614.24:527:03
1714.24:517:04
1814.24:507:04
1914.34:497:05
2014.34:487:06
2114.34:477:07
2214.44:477:08
2314.44:467:09
2414.44:457:10
2514.44:447:11
2614.54:447:12
2714.54:437:12
2814.54:437:13
2914.54:427:14
3014.64:427:15
3114.64:417:16

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.79 kWh/m².

For context, solar energy here swings from a low near 1.84 kWh/m² to a high of 6.46 kWh/m² in June across the year — May's 5.79 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
75.6Bright
85.6Bright
95.6Bright
105.7Bright
115.7Bright
125.7Bright
135.8Bright
145.8Bright
155.8Bright
165.8Bright
175.9Bright
185.9Bright
195.9Bright
205.9Bright
215.9Bright
226.0Bright
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 Jacksonville?

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

6.2
Sightseeing
3rd-best month of the year
4.8
Beach & pool
5th-best month of the year

May is a reasonable time to visit Jacksonville for sightseeing.

What to pack for Jacksonville in May

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

In May, Jacksonville sees daytime highs around 74°F and nights near 55°F. Worth packing: light clothes, rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

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

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJun 21UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep7High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Jacksonville 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 Jacksonville is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodJul 1716 µg/m³Oct 238 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar12Moderate
Apr11Good
May14Moderate
Jun14Moderate
Jul16Moderate
Aug14Moderate
Sep11Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Jacksonville?

Jacksonville sits at 39.7°N, 90.2°W, 610 ft above sea level, in United States. The nearest listed city is Springfield, 32 mi away.

Topography around Jacksonville

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

Within 2 miles, the terrain around Jacksonville has only modest variations in elevation — a maximum elevation change of 177 ft around an average of 604 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 243 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 604 ft.

The land around Jacksonville is covered by trees (32%), grassland (25%) and cropland (23%) within 2 miles, cropland (74%) within 10 miles, and cropland (65%) and trees (27%) within 50 miles.

2 miles
177 ft
10 miles
243 ft
50 miles
604 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Springfield 32 mi · Godfrey 54 mi · Macomb 55 mi · Upper Alton 57 mi · Alton 58 mi · Hannibal 60 mi · Old Jamestown 62 mi · Quincy 64 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 Jacksonville (39.7339°, -90.229°, elevation 610 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. 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).