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

Oswego, Illinois Weather

Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →

Oswego weather forecast — hour by hour, 7-day outlook, NOAA radar

Oswego, IL
Saturday, July 4 at 10:53 AM
79
°
Partly Cloudy
Feels like
87°
Humidity
77%
Wind
5 mph
Sunrise
12:24 AM
Sunset
3:31 PM
Oswego, IL
Hour by hour · 24h
24-Hour ForecastOswego, IL: 24-hour forecast. Temperatures range from 65 to 81 degrees Fahrenheit with a 51% chance of precipitation at 7 PM.
L 65°H 81°
Oswego, IL
7-day forecast
  1. Today
    Jul 4
    Heavy Showers
    82%
    0.91″
    81°69°—
  2. Sunday
    Jul 5
    Overcast
    17%
    —
    79°65°-2°
  3. Monday
    Jul 6
    Overcast
    —
    —
    81°63°+2°
  4. Tuesday
    Jul 7
    Overcast
    —
    —
    81°59°0°
  5. Wednesday
    Jul 8
    Overcast
    11%
    —
    81°61°0°
  6. Thursday
    Jul 9
    Thunderstorm
    52%
    0.21″
    78°65°-3°
  7. Friday
    Jul 10
    Overcast
    45%
    —
    82°62°+4°
Oswego, IL
Next 24 hours · Mild now
62°74°86°6a12p6p12anow 77°high 81°low 65°PRECIP %
Oswego, IL
Anemometer · 24h winds · from true
NESW
From · True
S
173° · backing 45°
Direction
S
173°
Sustained
5
mph
Gust
7
mph
Peak 24h
17
avg 5
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 5 · pk 17 @ 1:00p
0102030MPHB1B2B3B4B5B6-21h-18h-15h-12h-9h-6h-3h-24hNOWpk 277SUSTGUST
−24h−18h−12h−6hnow
A whisper of wind — leaves barely shift on the trees.
Oswego, IL
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
990.7
+0.2 mb in 3h · steady · 29.26 inHg
Now
990.7
mb
3h
+0.2
mb
12h
-0.6
mb
24h
-3.5
mb
Regime · STORM
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 991–994
9859909951000STORM|RAIN-21h-18h-15h-12h-9h-6h-3h-24hNOW994.4990.6990.9
−24h−18h−12h−6hnow
Deep low — expect rough seas, strong wind, and persistent rain.
Oswego, IL
Air quality
30
AQI
Good
→-3 in 6h▲Peak ~39 @ 10 PM

AQI 30 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM scrubbed by 2 hours of recent rain — PM2.5 down to 6.8 µg/m³, PM10 to 7.4 µg/m³.

OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 10 PM.

PM 2.5DRIVERGood
6.8μg/m³
PM 10Good
7μg/m³
NO₂Good
7μg/m³
OzoneModerate
66μg/m³
UV IndexLow
1.9

What's driving it

Ozone × UV × Sky

Ozone at AQI 31. Overcast through the UV peak window (cloud cover ~76%) — afternoon ozone should stay flat.

Present
AQI 31
UV peak
2.7 at 1 PM
Sky at peak
overcast
Projected peak
AQI 6

PM × Wind × Precip

PM scrubbed by 2 hours of recent rain — PM2.5 down to 6.8 µg/m³, PM10 to 7.4 µg/m³.

PM2.5/PM10
0.92
Wind
light
Recent rain
2h in last 6h
Pattern
washed out

Trends

Seven days of AQI and PM2.5.

Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).

7-DAY AQI TREND50100SATSUNMONTUEWEDTHUFRISAT7-DAY PM2.5 TREND · μg/m³300
Oswego, IL
Sky cover · visibility · 24h
Cloud cover
76%
MOSTLY CLOUDY
100%0%−24h−18h−12h−6hnow
Visibility
40.2mi
UNLIMITED
55 mi0 mi−24h−18h−12h−6hnow
Earth · GOES-19 ABI
Full Disk · Visible · GeoColor
GOES-19 full disk Visible · GeoColor
True-color daytime, blue/IR sandwich at night
15:53 UTC · Oswego, IL · NOAA NESDIS / STAR · up to 10848 px
Continental US · GOES-19 ABI
CONUS Sector · Visible · GeoColor
GOES-19 CONUS Visible · GeoColor
Daytime true-color, blue-light/IR sandwich at night
15:53 UTC · Oswego, IL · NOAA NESDIS / STAR · 5-min cadence · up to 10000 px
Oswego, IL
Satellite · infrared · animated
Oswego, IL
Loading IR frames…
IR · cloud-top temp© RainViewer · Carto
Oswego, IL
Almanac · Saturday, July 4
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
Civil dawn
4:51 AM
Sunrise
12:24 AM
Daylight
15h 07m
Sunset
3:31 PM
Civil dusk
9:06 PM
Planting note
Harvest early potatoes. Begin drying onions on the surface.
Oswego, IL
The moon
Waning Gibbous
80% illuminated
Moonrise
10:50 PM
Moonset
9:57 AM
In sign
♓︎ Pisces
Oswego, IL
Microseason
Jul 1–5

Cicadas claim the afternoon

plant
Jan 151% of the yearDec 31

Read this microseason across nine climate regions →

Oswego at a glance

  • Today vs. normal: 9°F above the seasonal normal for this latitude
  • Last frost: April 26 (climatological average for this latitude)
  • Microseason: Jul 1–5
  • Planting window: Harvest early potatoes. Begin drying onions on the surface.

ZIP code: 60543

16-Day Forecast — Oswego

  1. Sat81°69°82%
  2. Sun79°65°17%
  3. Mon81°63°2%
  4. Tue81°59°1%
  5. Wed81°61°11%
  6. Thu78°65°52%
  7. Fri82°62°45%
  8. Sat81°62°16%
  9. Sun68°58°7%
  10. Mon74°56°7%
  11. Tue78°60°7%
  12. Wed79°62°26%
  13. Thu82°65°21%
  14. Fri83°69°29%
  15. Sat85°70°23%
  16. Sun83°70°31%

Forecast data from Open-Meteo (CC BY 4.0).

Right now in the garden

Peak growing season

As of July 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.

SPC Convective Outlook

Storm Prediction Center — Oswego

SPC has placed Oswego in the Marginal Risk category for severe thunderstorms today.

  • TODAYMRGLMarginal Risk
  • TOMORROWTSTMGeneral Thunderstorms
  • DAY 3NONENo severe risk

Isolated severe storms possible. Limited threat for hail or damaging wind.

Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.

January 1–5: The year turns in silence.January 6–10: Ice thickens on still water.January 11–15: Shortest shadows lengthen.January 16–20: Pheasants begin to call.January 21–25: Springs begin to thaw.January 26–31: Chickadees announce dawn.February 1–5: East wind softens the frost.February 6–10: Sap begins to rise.February 11–15: First snowdrops appear.February 16–20: Red-winged blackbirds return.February 21–25: Rain begins to replace snow.February 26–28: Skunk cabbage pushes through ice.March 1–5: Ice withdraws from the reservoir.March 6–10: Crocuses open to weak sun.March 11–15: Peepers call from the marsh.March 16–20: Woodcocks spiral at dusk.March 21–25: Equinox — light overtakes dark.March 26–31: Forsythia opens along the fences.April 1–5: Cherry blossoms drift like snow.April 6–10: Warblers appear in the understory.April 11–15: Magnolias bloom and fall in a day.April 16–20: Dogwoods float above the forest.April 21–25: Lilacs perfume the evening.April 26–30: Last frost releases the garden.May 1–5: Warblers flood the Ramble.May 6–10: Tulip poplars light their candles.May 11–15: Shad run up the rivers.May 16–20: Roses open along the stoops.May 21–25: Firefly scouts appear at dusk.May 26–31: Strawberries ripen in the sun.June 1–5: Fireflies rise from the lawn.June 6–10: Elderflowers open in hedgerows.June 11–15: Solstice approaches — longest light.June 16–20: Honeysuckle sweetens the night.June 21–25: Solstice — the sun stands still.June 26–30: Lightning bugs drift through oaks.July 1–5: Cicadas claim the afternoon.July 6–10: Queen Anne's lace lines the roads.July 11–15: Thunder builds each afternoon.July 16–20: Corn reaches for the tassels.July 21–25: Dog days settle in the haze.July 26–31: Katydids begin their chorus.August 1–5: Night falls a minute earlier.August 6–10: Sunflowers face the morning.August 11–15: Goldenrod begins to bloom.August 16–20: Crickets pulse through warm nights.August 21–25: First cool morning surprises.August 26–31: Monarchs stage for flight.September 1–5: School buses reappear.September 6–10: Asters purple the roadsides.September 11–15: Hawk migration over the Hudson.September 16–20: Equinox — dark overtakes light.September 21–25: Apples hang heavy on the branch.September 26–30: Geese begin to chevron south.October 1–5: Witch hazel blooms as others fade.October 6–10: Maples begin to blaze.October 11–15: Frost paints the garden black.October 16–20: Oaks turn bronze and russet.October 21–25: Leaves rattle down the gutters.October 26–31: Clocks fall back — dusk at five.November 1–5: Ginkgos drop overnight.November 6–10: Last leaves cling stubbornly.November 11–15: Juncos arrive from the north.November 16–20: Bare branches reveal the sky.November 21–25: First flurries dust the rooftops.November 26–30: Woodsmoke curls through the block.December 1–5: Darkness settles before dinner.December 6–10: Holly and winterberry persist.December 11–15: Shortest day approaches.December 16–20: Ice begins to form at the edges.December 21–25: Solstice — the sun begins return.December 26–31: The year turns in silence.🌱February 14 — First skunk-cabbage spathes thaw their way up☀️March 20 — Spring equinox — day and night balance🌸April 5 — Cherry blossoms peak in the parks🐦May 10 — Warbler migration peaks along the coast✨May 25 — First fireflies scout the meadows at dusk🌞June 21 — Summer solstice — longest day🦗July 25 — Peak cicada chorus in the afternoons🌊August 18 — Warmest sea-surface temperatures of the year🍂September 22 — Autumn equinox — the slow turn❄️October 25 — First widespread frost in the suburbs🍁November 10 — Peak leaf color across the Hudson Valley🌙December 21 — Winter solstice — longest night

Microseason · July 1–5

Cicadas claim the afternoon

Annual cicada buzz begins, peaking in the heat of the day.

Day 185 of 365 · Wedge 37 of 72

The solar year drawn as a wheel of 72 five-day windows. Each wedge is one microseason; the four colored arcs mark winter, spring, summer, and autumn; the small icons sit at notable phenological events. The crimson pointer creeps clockwise as the year turns.

Planting calendar

MonthPlantHarvest
January——
February——
March——
Aprillettuce, peas, spinach, radishes—
Maylettuce, peas, spinach, radishes, tomatoes, peppers, beans, squashlettuce, peas, radishes
Junetomatoes, peppers, beans, squashlettuce, peas, radishes
Julytomatoes, peppers, beans, squashtomatoes, beans, summer squash
August—tomatoes, beans, summer squash
Septemberfall brassicas, garlic (overwinter), carrotstomatoes, beans, summer squash
Octoberfall brassicas, garlic (overwinter), carrotswinter squash, tomatoes (last)
November——
December——

A year in weather

Oswego's warmest month is July (~76°F mean) and its coldest is January (~23°F). Rainfall peaks in May (4.3 inches) and bottoms out in January (1.7 inches).

MonthMean tempPrecipRainy days
January23°1.7″14
February26°1.9″13
March37°2.9″15
April50°3.8″17
May59°4.3″18
June70°4.0″15
July76°2.9″14
August75°3.1″14
September67°3.1″13
October55°2.9″11
November40°3.0″12
December27°2.2″13

Regional context

In Oswego, NOAA NCEI 1991-2020 normals put January near 23°F and July near 76°F — a 53°F seasonal arc — with about 35.8 inches of precipitation over 170 rainy or snowy days.

Summer convection drives Oswego's precipitation: May logs 4.3 inches on 17.9 rainy days, against January's 1.7 inches on 14.3 — warm-season storms carry Oswego's moisture. It is a warm-season-wet pattern Oswego shares with places like Boulder Hill, IL, Montgomery, IL and Aurora, IL.

Around mid-April, Oswego sheds its freezing nights — kale, peas, spinach, and parsnips go into Oswego's beds. Tomatoes and peppers do best set out two weeks later in Oswego, once nights clear the mid-40s°F. By mid-November, frost is back in Oswego — protect or harvest anything tender. Oswego's low ground holds frost later into spring than Oswego's benches, which run 3-5 days ahead.

Similar climates: Boulder Hill, IL, Montgomery, IL, Aurora, IL, Yorkville, IL, Plainfield, IL.

Frequently asked

When does it freeze in Oswego?
Frost typically leaves Oswego by mid-April and returns to Oswego near mid-November.
What is the rainy season in Oswego?
May is the wettest month in Oswego, about 4.3 inches on average; the year totals roughly 36 inches.
What is the warmest month in Oswego?
Oswego peaks in July, when the mean runs near 76°F.
What is the coldest month in Oswego?
January is Oswego's coldest month, averaging about 23°F.
When can I start a vegetable garden in Oswego?
Around mid-April, start frost-hardy crops in Oswego; tomatoes and basil belong a fortnight later.
How many rainy days does Oswego get?
Oswego records around 170 days of measurable precipitation annually.
What hardiness zone is Oswego?
Because Oswego bottoms near 23°F in January, that winter low sets Oswego's USDA zone — verify by ZIP.
What is the 10-day forecast for Oswego?
Oswego's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
Will it rain this week in Oswego?
See this week's day-by-day rain chances for Oswego in the daily forecast above, and the next 24 hours in the hourly chart.
What is the weather like right now in Oswego?
Current conditions for Oswego and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
How often is the Oswego forecast updated?
The Oswego forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
When are sunrise and sunset in Oswego?
Today's sunrise and sunset times for Oswego are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
How accurate is the weather forecast for Oswego?
The next few days in Oswego's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.

Climate

In Oswego, Illinois, the warm-summer humid continental climate runs from about 23°F in January to 76°F in July, a 53°F seasonal range.

Oswego sees close to 36 inches of precipitation annually, falling across some 170 wet days.

From 41.7°N, Oswego sees a 53°F seasonal swing that governs Oswego's planting and frost windows.

All cities in Illinois →

Chicago, IL weather →

ZIP codes in Oswego

  • 60543

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.