41.3540, -87.1850

1. Sat11 PM54°3 mph
2. Sun12 AM52°5 mph
3. 1 AM52°5 mph
4. 2 AM51°2%2 mph
5. 3 AM50°2%3 mph
6. 4 AM48°3 mph
7. 5 AM47°1%3 mph
8. 6 AM47°3 mph
9. 7 AM49°3 mph
10. 8 AM53°5 mph
11. 9 AM58°7 mph
12. 10 AM63°7 mph
13. 11 AM67°8 mph
14. 12 PM69°8 mph
15. 1 PM71°9 mph
16. 2 PM72°9 mph
17. 3 PM72°9 mph
18. 4 PM70°10 mph
19. 5 PM68°9 mph
20. 6 PM64°7 mph
21. 7 PM60°6 mph
22. 8 PM57°5 mph
23. 9 PM56°5 mph
24. 10 PM55°6 mph
25. 11 PM53°6 mph
26. Mon12 AM52°5 mph
27. 1 AM52°6 mph
28. 2 AM51°6 mph
29. 3 AM50°5 mph
30. 4 AM49°5 mph
31. 5 AM47°5 mph
32. 6 AM46°5 mph
33. 7 AM47°2 mph
34. 8 AM51°3 mph
35. 9 AM56°5 mph
36. 10 AM61°5 mph
37. 11 AM64°5 mph
38. 12 PM65°6 mph
39. 1 PM65°6 mph
40. 2 PM66°6 mph
41. 3 PM65°7 mph
42. 4 PM64°6 mph
43. 5 PM61°6 mph
44. 6 PM57°5 mph
45. 7 PM54°5 mph
46. 8 PM50°3 mph
47. 9 PM48°3 mph
48. 10 PM47°2 mph

Scroll sideways for more hours. Pick an hour for every number.

1. TodayOct 370°47°Mostly Clear0%wind 7 mph
2. SunOct 472°46°Sunny2%wind 10 mph
3. MonOct 566°40°Sunny0%wind 7 mph
4. TueOct 668°49°Sunny0%wind 9 mph · gusts 15 mph
5. WedOct 773°48°Sunny2%wind 9 mph
6. ThuOct 871°48°Sunny3%wind 7 mph
7. FriOct 971°49°Sunny4%wind 8 mph · gusts 14 mph
8. SatOct 1076°57°Sunny3%wind 10 mph · gusts 17 mph
9. SunOct 1175°55°National Blend16%wind 9 mph · gusts 15 mph
10. MonOct 1271°52°National Blend36%0.08 inwind 10 mph · gusts 17 mph
11. TueOct 1365°47°National Blend39%0.12 inwind 12 mph · gusts 18 mph
12. WedOct 14~70°58°Model mean0.10 in
13. ThuOct 15~69°57°Model mean0.18 in
14. FriOct 16~56°47°Model mean
15. SatOct 17~54°38°Model mean
16. SunOct 18~68°51°Model mean

• Feels like54°
• WindSE 3 mphgusts 7 mph
• Radar over this pointno reading
• Humidity80%
• Dew point48°
• Pressure—
• UV index—
• Air quality—
• Visibility—
• Sunrise and sunsetSunrise · Sunset · set
• Moonrise11:45 PMMoonset 2:44 PM
• Moon phaseLast quarter53% lit

NOAA’s weighted blend of every model it runs, to eleven days, with the chances the grid above does not carry. Where the local office’s grid reaches, its figure sits beneath the blend’s; where it does not, the blend stands alone.

1. TodayOct 3—44°NWS grid 70° / 47°rain 1%wind 3 mph
2. SunOct 471°46°NWS grid 72° / 46°rain 1%wind 8 mph
3. MonOct 565°41°NWS grid 66° / 40°rain 0%wind 6 mph
4. TueOct 668°49°NWS grid 68° / 49°rain 0%wind 10 mph
5. WedOct 772°48°NWS grid 73° / 48°rain 1%wind 8 mph
6. ThuOct 870°48°NWS grid 71° / 48°rain 6%wind 7 mph
7. FriOct 970°48°NWS grid 71° / 49°rain 4%wind 8 mph
8. SatOct 1075°54°NWS grid 76° / 57°rain 4%wind 10 mph · gusts 16 mph
9. SunOct 1175°55°Beyond the NWS gridrain 16%wind 9 mph · gusts 15 mph
10. MonOct 1271°52°Beyond the NWS gridrain 36%0.08 inwind 10 mph · gusts 17 mph
11. TueOct 1365°47°Beyond the NWS gridrain 39%0.12 inwind 12 mph · gusts 18 mph
12. WedOct 1464°—Beyond the NWS gridrain 15%wind 9 mph · gusts 15 mph

Each line is one model’s own forecast at its own grid cell: three kilometers for HRRR, a quarter of a degree for the global models, which can sit a few hundred meters above or below the town. Where they agree the forecast is settled; where they part is where it is not.

NWS gridBlendHRRRGFSGEFS ± spreadECMWFECMWF AI

A ~ marks a high or low read from six-hourly steps, which miss the true extreme by a degree or two.

ECMWF ensemble meteogram

10 daysTemperature plume

No forecast has skill day by day past about two weeks, and this page does not print one. Where the models stop, the calendar takes over: the 1991 to 2020 normal for each date, the record high and low ever set on it, and where the Climate Prediction Center leans warm, cool, wet or dry over the coming weeks, the month and the season. A site that shows a high for a date three months out is showing you this normal with a wobble.

The forecast reaches Sun Oct 18, from the NWS grid, then the National Blend, then the mean of the global models. Beyond it the lines are the calendar.

Forecast high and lowNormal high and lowRecord high and lowCPC leans warmer than normalCPC near normal or equal chances

None of these is a measurement. Each is a rating of the forecast ahead, and of what is happening at the point right now, against what the activity or the ailment is known to mind, and each names the figure that decided it. An ailment or a pest is rated as a risk, low to extreme; an activity, a chore or a journey as a condition, poor to ideal.

The sun is down, so each rating says which span it is for: tomorrow’s daylight, tonight, or the next 24 hours.

Tonight: 3 dark, clear hours without a bright moon, from 8:00 PM. Rated good.

Dark is the sun 18 degrees below the horizon; where it never gets that low, 12 degrees, marked nautical. Clear is sky cover of 20% or less. A bright moon is one above the horizon with a quarter or more of its disc lit. Transparency in the table is estimated from surface humidity (70% and 85% mark fair and poor) and visibility, since the forecast carries no haze or high cloud moisture. Seeing and transparency by hour, where shown, are Environment and Climate Change Canada’s astronomy forecast (regional model; seeing from cloud, wind shear, turbulence near the ground and the surface temperature trend; transparency from the moisture through the whole air column), under the Open Government Licence - Canada. Dew is the air within 2 °C of its dew point. Excellent is four or more clear moonless hours with good transparency; good is three; fair is one, or two clear hours.

Golden hour is the sun between 6 degrees above the horizon and 4 degrees below it; blue hour is the sun between 4 and 6 degrees below. These are the definitions timeanddate.com and PhotoPills use. Directions are degrees clockwise from true north, where the sun’s upper edge and the moon’s center cross a flat horizon; hills and buildings change both. None means the sun does not reach that height on the day; all day means it stays inside the band.

This hour: fly with caution (night: lighting and night training required (107.29)). Next good stretch: Sun 7 AM to 6 PM, 11 hours.

Today: civil twilight for Part 107 6:18 AM to sunrise 6:48 AM, and sunset 6:27 PM to 6:57 PM. Anti-collision lighting is required in those minutes and at night.

Good Caution No-fly

Flight restrictions nearby

Reading the FAA’s temporary flight restrictions.

Flight restrictions on the map. TFRs are not the whole picture: controlled airspace around airports needs LAANC authorization. Check the FAA’s B4UFLY.

Wind at 400 ft is estimated from the 10 m forecast by the power law, with exponents for each Pasquill stability class (Irwin 1979, rural, as in EPA dispersion models; the class from wind, sun height and cloud, after Turner 1970); gusts keep the ground gust’s margin. Caution from three quarters of your limit; the default 24 mph is the wind resistance printed for common sub-250 g drones. 14 CFR 107.51: “The minimum flight visibility, as observed from the location of the control station must be no less than 3 statute miles” and at least “500 feet below the cloud”. 14 CFR 107.29: “No person may operate a small unmanned aircraft system during periods of civil twilight unless the small unmanned aircraft has lighted anti-collision lighting visible for at least 3 statute miles”; civil twilight is the 30 minutes before sunrise and after sunset, in Alaska the Air Almanac’s. Kp: SWPC’s scales say satellite navigation problems may occur at G3 (Kp 7) and navigation is “degraded for hours” at G4 (Kp 8); Kp 5 is the typical app warning. Typical limits, not rules: rain chance 30% caution and 60% no-fly, thunder 10% and 20%, below 0 °C caution and −10 °C no-fly, over 40 °C caution. Your drone’s manual and the airspace come first.

Hours fit for spraying, and the days dry enough for fieldwork and hay, read from this forecast’s wind, gusts, humidity, temperature and rain.

Spraying windows

• Sun 8 AM to 4 PM 8 hours, every hour within the rules
• Sun 5 PM to 9 PM 4 hours, every hour within the rules
• Mon 9 AM to 8 PM 11 hours, every hour within the rules
• Tue 9 AM to Thu 4 AM 43 hours, every hour within the rules
• Thu 9 AM to 9 PM 12 hours, every hour within the rules
• Fri 1 AM to Sat 11 AM 34 hours, every hour within the rules

Good Marginal No

Field days

Spraying: sustained wind 3 to 10 mph, the range US extension services and most labels give; gusts no more than 15 mph (this page’s limit); delta T (air minus wet-bulb temperature) 2 to 8 °C preferred and 8 to 10 °C marginal, from GRDC guidance, with the wet bulb by Stull’s formula; no hour at a 30% chance of rain or 0.25 mm forecast during the rain-free time. Follow the product label, which overrides all of this. Field days: dry is no daytime hour at a 30% chance and under 1 mm all day, wet is 6 mm (0.25 in) or more; soil moisture is not in the forecast, so ground still wet from earlier rain is not accounted for. Hay drying marks a dry day with humidity down to 50% and a breeze of 5 mph or more.

The best-rated day this week is Friday, rated best.

Periods in bold fall within an hour of sunrise or sunset. The weather’s side is the fishing index

Major periods are two hours centered on the moon’s passage overhead and underfoot; minor periods are one hour centered on moonrise and moonset: the conventional durations of John Alden Knight’s solunar tables (1936). The rating is this site’s: one point to start, two more within a day and a half of a new or full moon (one more within three and a half days), and one more when a period falls within an hour of sunrise or sunset. The theory has mixed support in fisheries research; the times are exact astronomy.

1. Tonight47° · 2% · SSE 0–5 mph

   Mostly clear, with a low around 47. South southeast wind 0 to 5 mph.

2. Sunday72° · WNW 5–10 mph

   Sunny. High near 72, with temperatures falling to around 68 in the afternoon. West northwest wind 5 to 10 mph.

3. Sunday Night46° · NNW 5 mph

   Mostly clear, with a low around 46. North northwest wind around 5 mph, with gusts as high as 10 mph.

4. Monday66° · N 0–5 mph

   Sunny, with a high near 66. North wind 0 to 5 mph.

5. Monday Night40° · E 0–5 mph

   Clear, with a low around 40. East wind 0 to 5 mph.

6. Tuesday68° · S 0–10 mph

   Sunny, with a high near 68.

7. Tuesday Night49° · SSW 5–10 mph

   Mostly clear, with a low around 49.

8. Wednesday73° · 2% · WSW 5–10 mph

   Sunny, with a high near 73.

9. Wednesday Night48° · 1% · WNW 0–5 mph

   Mostly clear, with a low around 48.

10. Thursday71° · 1% · NW 0–5 mph

    Sunny, with a high near 71.

11. Thursday Night48° · 3% · WSW 0–5 mph

    Mostly clear, with a low around 48.

12. Friday71° · 4% · SW 5–10 mph

    Sunny, with a high near 71.

13. Friday Night49° · 1% · SE 5 mph

    Mostly clear, with a low around 49.

14. Saturday76° · 1% · S 5–10 mph

    Sunny, with a high near 76.

Written by the forecaster on duty for their own colleagues and for anyone who wants to know why the forecast says what it says. It is not edited for the public, so it uses the office’s shorthand; it is also the most honest thing any weather service publishes.

FLUS43 KLOT 031941
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
241 PM CDT Sat Oct 3 2026

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-050000-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
241 PM CDT Sat Oct 3 2026 /341 PM EDT Sat Oct 3 2026/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Tonight.

  No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

  No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

$$

LMZ740>745-050000-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
241 PM CDT Sat Oct 3 2026

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

  No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Sunday Night and Monday Morning...
  Hazardous conditions for small craft are likely for
   Indiana nearshore.

$$

DK

Visit us at www.weather.gov/chicago

The national centers each publish a judgment the local grid does not carry. Read here at this exact coordinate.

The last spring freeze (32°F) usually comes around April 22 and the first fall freeze around October 25: a growing season of about 185 days.

One fall in ten brings a freeze by October 12; one spring in ten still has one after May 6.

Climate of 41.35, -87.19: normals, records and every month

The forecast office edits about sixty fields for every cell of its grid. The common ones are above; these are the rest, as the daily extreme, for anyone who needs the mixing height, the fire danger or the swell.

Each forecast day against the same calendar date at the nearest long-record station: the 1991 to 2020 normal, and the record high and low with the year they were set.