Weather StoryAlmanac, microseasons, and the day's weather story.

Weather in Alton, Illinois

Roses open on the Piedmont edge. Day 59 of spring. Read this microseason across nine climate regions →

Alton, IL
Sunday, May 17 at 5:02 AM
66
°
Clear
Feels like
68°
Humidity
90%
Wind
6 mph
Sunrise
5:45 AM
Sunset
8:08 PM
Alton, IL
Hour by hour · 24h
60°
12a
60°
1a
59°
2a
58°
3a
58°
4a
59°
17%
5a
60°
34%
6a
59°
27%
7a
61°
10%
8a
63°
10%
9a
66°
10a
70°
11a
74°
12p
78°
1p
80°
2p
83°
3p
83°
4p
81°
5p
80°
6p
78°
7p
76°
8p
74°
9p
74°
10p
73°
11p
L 58°H 83°
Alton, IL
7-day forecast
  1. Today
    May 17
    Overcast
    —
    86°65°
  2. Monday
    May 18
    Heavy Rain
    52%
    77°68°
  3. Tuesday
    May 19
    Showers
    89%
    78°60°
  4. Wednesday
    May 20
    Overcast
    59%
    66°50°
  5. Thursday
    May 21
    Drizzle
    13%
    65°50°
  6. Friday
    May 22
    Light Drizzle
    18%
    64°53°
  7. Saturday
    May 23
    Drizzle
    15%
    79°60°
Alton, IL
Next 24 hours · Cool now
HOT 90°50°70°90°12a6a12p6pnow 60°high 83°low 58°PRECIP %
Alton, IL
Anemometer · 24h winds · from true
NESW
From · True
SE
129° · veering 43°
Direction
SE
129°
Sustained
6
mph
Gust
13
mph
Peak 24h
22
avg 6
Beaufort · 2 · LIGHT BRZ
0
CALM
<1
1
LIGHT AIR
1–3
2
LIGHT BRZ
4–7
3
GENTLE BRZ
8–12
4
MOD BRZ
13–18
5
FRESH BRZ
19–24
6
STRONG BRZ
25–31
7
NEAR GALE
32–38
24h · sust vs gust · mph
avg 6 · pk 22 @ 8:00a
−24h−18h−12h−6hnow
Light breeze veering 43° from the se.
Alton, IL
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
991.5
-0.2 mb in 3h · falling · 29.28 inHg
Now
991.5
mb
3h
-0.2
mb
12h
-0.5
mb
24h
+0.4
mb
Regime · STORM
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 991–995
−24h−18h−12h−6hnow
Deep low — expect rough seas, strong wind, and persistent rain.
Alton, IL
Air quality
35
AQI
Good
PM 2.5
4.9 μg/m³
PM 10
5.4 μg/m³
NO₂
8.6 μg/m³
Ozone
77.0 μg/m³
UV Index
0.0 Low
Alton, IL
Almanac · Sunday, May 17
When the dew is on the grass, rain will never come to pass.
Civil dawn
10:18 AM
Sunrise
5:45 AM
Daylight
14h 23m
Sunset
8:08 PM
Civil dusk
1:38 AM
Planting note
Direct sow okra, melons, and southern peas. Thin carrot rows.
Alton, IL
The moon
New Moon
0% illuminated
Moonrise
10:54 AM
Moonset
1:35 AM
In sign
♊︎ Gemini
Alton, IL
Microseason · 28 of 72
May 16–20

Roses open on the Piedmont edge

insect
Jan 137% of the yearDec 31

Read this microseason across nine climate regions →

Alton at a glance

  • Today vs. normal: 7°F below the seasonal normal for this latitude
  • Last frost: April 9 (climatological average for this latitude)
  • Microseason: 28 of 72, May 16–20
  • Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.

Right now in the garden

Warm-season window is open

As of May 17, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.

All cities in Illinois →

ZIP codes in Alton

Climate normals from the Open-Meteo Climate API. Köppen approximation from NOAA NCEI U.S. Climate Regions. See methodology for data sources, editorial rules, and corrections. Maintainer: Brian Tighe.