KORD — CHICAGO O'HARE
Chicago O'Hare, IL, US · America/Chicago · 41.9602°, -87.9316° · 200m elevation
Daily METAR Observations
| Time | Temperature | Dew Point | Humidity | Wind | Wind Speed | Wind Gust | Pressure | Precip. | Condition |
|---|---|---|---|---|---|---|---|---|---|
| 4:51 PM | 22 °F 21.9 °F -6 °C -5.6 °C | 3 °F 3 °F -16 °C -16.1 °C | 43 % | WSW | 6 mph 5 kt 9 km/h | 17 mph 15 kt 28 km/h | 30.15 in | 0.0 in | Overcast |
| METAR KORD 172151Z 24005G15KT 10SM OVC250 M06/M16 A3015 RMK AO2 SLP221 T10561161 | |||||||||
| 5:51 PM | 22 °F 21.9 °F -6 °C -5.6 °C | 4 °F 3.9 °F -16 °C -15.6 °C | 45 % | SSW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 30.17 in | 0.0 in | Overcast |
| METAR KORD 172251Z 20009KT 10SM OVC250 M06/M16 A3017 RMK AO2 SLP228 T10561156 | |||||||||
| 6:51 PM | 22 °F 21.9 °F -6 °C -5.6 °C | 4 °F 3.9 °F -16 °C -15.6 °C | 45 % | SSW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 30.17 in | 0.0 in | Overcast |
| METAR KORD 172351Z 21009KT 10SM BKN120 OVC250 M06/M16 A3017 RMK AO2 SLP228 T10561156 11044 21061 53004 | |||||||||
| 7:51 PM | 22 °F 21.9 °F -6 °C -5.6 °C | 6 °F 6.1 °F -14 °C -14.4 °C | 50 % | SW | 12 mph 10 kt 19 km/h | 0 mph 0 kt 0 km/h | 30.17 in | 0.0 in | Overcast |
| METAR KORD 180051Z 22010KT 10SM BKN110 OVC250 M06/M14 A3017 RMK AO2 SLP229 T10561144 | |||||||||
| 8:51 PM | 22 °F 21.9 °F -6 °C -5.6 °C | 7 °F 7 °F -14 °C -13.9 °C | 52 % | SW | 7 mph 6 kt 11 km/h | 0 mph 0 kt 0 km/h | 30.16 in | 0.0 in | Overcast |
| METAR KORD 180151Z 22006KT 10SM SCT095 BKN130 BKN200 OVC250 M06/M14 A3016 RMK AO2 SLP224 T10561139 | |||||||||
| 9:51 PM | 23 °F 23 °F -5 °C -5 °C | 9 °F 9 °F -13 °C -12.8 °C | 54 % | S | 6 mph 5 kt 9 km/h | 0 mph 0 kt 0 km/h | 30.16 in | 0.0 in | Overcast |
| METAR KORD 180251Z 19005KT 10SM OVC095 M05/M13 A3016 RMK AO2 SLP224 T10501128 55004 $ | |||||||||
| 10:51 PM | 23 °F 23 °F -5 °C -5 °C | 10 °F 10 °F -12 °C -12.2 °C | 57 % | S | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 30.16 in | 0.0 in | Overcast |
| METAR KORD 180351Z 19009KT 10SM BKN070 OVC160 M05/M12 A3016 RMK AO2 SLP224 T10501122 $ | |||||||||
| 11:51 PM | 24 °F 24.1 °F -4 °C -4.4 °C | 12 °F 12 °F -11 °C -11.1 °C | 59 % | S | 8 mph 7 kt 13 km/h | 0 mph 0 kt 0 km/h | 30.14 in | 0.0 in | Overcast |
| METAR KORD 180451Z 19007KT 10SM BKN060 OVC075 M04/M11 A3014 RMK AO2 SLP217 T10441111 $ | |||||||||
Time Series
Summary
| Temperature (°F) Temperature (°C) | Actual | |
| High Temp | 24 24.1 -4 -4.4 | |
| Low Temp | 22 21.9 -6 -5.6 | |
| Day Average Temp | 22 22.5 -5 -5.3 | |
| Precipitation (in) | Actual | |
| Precipitation | 0.00 | |
| Dew Point (°F) Dew Point (°C) | Actual | |
| High | 12 12 -11 -11.1 | |
| Low | 3 3 -16 -16.1 | |
| Average | 7 6.9 -14 -14 | |
| Humidity (%) | Actual | |
| Average Humidity | 51% | |
| Wind (mph) Wind (kt) Wind (km/h) | Actual | |
| Max Wind Speed | 12 10 19 | |
| Max Wind Gust | 17 15 28 | |
| Visibility | - | |
| Pressure (in) | Actual | |
| Average Pressure | 30.16 | |
| Astronomy | Day Length | Rise / Set |
| Actual Time | 12h 3m | 6:58 AM / 7:01 PM |
| Civil Twilight | 6:31 AM / 7:28 PM | |
| Nautical Twilight | 5:59 AM / 8:00 PM | |
| Astronomical Twilight | 5:26 AM / 8:33 PM | |
| Moon: New Moon | ||
Methodology
Day Boundaries & Time
A "day" is defined as midnight to midnight (00:00:00 through 23:59:59) in the station's local time, using the IANA timezone assigned to each station (e.g. America/Chicago, Europe/London). Daylight Saving Time transitions are respected automatically — when a station's local clocks spring forward or fall back, the UTC boundaries of the day shift accordingly. This means a "day" in the spring DST transition is 23 hours, and in the fall transition it is 25 hours. All observations are stored internally in UTC and converted to local time for display.
Temperature
The FAA reports temperature in degrees Celsius. Values are stored to one decimal place — if a source value has additional precision, it is rounded on storage. Fahrenheit values are computed as °F = °C × 9/5 + 32. All temperatures are displayed as whole numbers (rounded to the nearest integer) in both Celsius and Fahrenheit. High and low temperatures are the maximum and minimum observed values for the day. The day average is the arithmetic mean of all observed temperatures, rounded to the nearest whole number.
Dew Point & Relative Humidity
Dew point is stored and displayed using the same rounding method as temperature (whole numbers). Relative humidity is not reported directly in METARs — it is calculated from the temperature and dew point using the Magnus formula: RH = 100 × exp[(17.27 × Td)/(237.7 + Td) − (17.27 × T)/(237.7 + T)], where T is temperature and Td is dew point, both in °C. The result is rounded to the nearest whole percent and clamped between 0% and 100%.
Wind
Wind direction is reported in degrees true (0–360). The compass direction shown (N, NNE, NE, etc.) divides the compass into 16 sectors of 22.5° each. Variable winds (reported as "VRB" in the METAR) are displayed as "CALM". Wind speed is reported in knots (integer). Miles per hour is computed as mph = kt × 1.15078 and kilometers per hour as km/h = kt × 1.852, both displayed as whole numbers. Wind gust is shown only when the METAR includes a gust value.
Pressure
The altimeter setting is reported in inches of mercury (inHg) to two decimal places. This is the station pressure corrected to sea level and is the value displayed. When the METAR also includes sea level pressure in millibars, that value is used in daily summary calculations.
Precipitation
Precipitation accumulations (1-hour, 3-hour, 6-hour, and 24-hour) are included when reported by the station. A value of 0.0005 inches represents trace precipitation in the FAA convention. The daily total in the summary is the sum of all 1-hour accumulations that exceed trace. Not all stations report precipitation data.
Sky Condition & Weather
The "Condition" column is derived from two METAR fields. If a weather phenomena code is present (e.g. RA for rain, SN for snow, FG for fog, TSRA for thunderstorms), it takes priority and the intensity prefix (- for light, + for heavy) is included. When no active weather is reported, the condition is derived from the highest sky cover layer: CLR/SKC/FEW = Fair, SCT = Partly Cloudy, BKN = Mostly Cloudy, OVC = Overcast.