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 |
|---|---|---|---|---|---|---|---|---|---|
| 12:51 AM | 61 °F 61 °F 16 °C 16.1 °C | 30 °F 30 °F -1 °C -1.1 °C | 31 % | WNW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 29.59 in | 0.0 in | Overcast |
| METAR KORD 050551Z 30009KT 10SM OVC100 16/M01 A2959 RMK AO2 SLP016 T01611011 10183 20161 402670106 53016 | |||||||||
| 1:51 AM | 59 °F 59 °F 15 °C 15 °C | 31 °F 30.9 °F -1 °C -0.6 °C | 34 % | NW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 29.60 in | 0.0 in | Overcast |
| METAR KORD 050651Z 31009KT 10SM BKN100 OVC150 15/M01 A2960 RMK AO2 SLP019 T01501006 | |||||||||
| 2:51 AM | 57 °F 57 °F 14 °C 13.9 °C | 32 °F 32 °F 0 °C 0 °C | 39 % | NNW | 13 mph 11 kt 20 km/h | 23 mph 20 kt 37 km/h | 29.62 in | 0.0 in | Overcast |
| METAR KORD 050751Z 33011G20KT 10SM BKN110 OVC150 14/00 A2962 RMK AO2 SLP026 T01390000 | |||||||||
| 3:51 AM | 55 °F 55 °F 13 °C 12.8 °C | 32 °F 32 °F 0 °C 0 °C | 41 % | NW | 14 mph 12 kt 22 km/h | 0 mph 0 kt 0 km/h | 29.67 in | 0.0 in | Overcast |
| METAR KORD 050851Z 32012KT 10SM OVC100 13/00 A2967 RMK AO2 SLP044 T01280000 53027 | |||||||||
| 4:51 AM | 51 °F 51.1 °F 11 °C 10.6 °C | 33 °F 33.1 °F 1 °C 0.6 °C | 50 % | NW | 7 mph 6 kt 11 km/h | 0 mph 0 kt 0 km/h | 29.71 in | 0.01 in | Light Rain |
| METAR KORD 050951Z 32006KT 10SM -RA FEW055 OVC100 11/01 A2971 RMK AO2 RAB41 SLP056 P0000 T01060006 | |||||||||
| 5:51 AM | 50 °F 50 °F 10 °C 10 °C | 31 °F 30.9 °F -1 °C -0.6 °C | 48 % | NNW | 15 mph 13 kt 24 km/h | 0 mph 0 kt 0 km/h | 29.73 in | 0.01 in | Overcast |
| METAR KORD 051051Z 34013KT 10SM FEW070 OVC100 10/M01 A2973 RMK AO2 RAE04 SLP066 P0000 T01001006 | |||||||||
| 6:51 AM | 49 °F 48.9 °F 9 °C 9.4 °C | 34 °F 34 °F 1 °C 1.1 °C | 56 % | WNW | 6 mph 5 kt 9 km/h | 0 mph 0 kt 0 km/h | 29.77 in | 0.01 in | Light Rain |
| METAR KORD 051151Z 30005KT 10SM -RA BKN050 BKN070 OVC250 09/01 A2977 RMK AO2 RAB27 SLP082 P0001 60001 70020 T00940011 10161 20089 53034 | |||||||||
Time Series
Summary
| Temperature (°F) Temperature (°C) | Actual | |
| High Temp | ||
| Low Temp | ||
| Day Average Temp | ||
| Precipitation (in) | Actual | |
| Precipitation | ||
| Dew Point (°F) Dew Point (°C) | Actual | |
| High | ||
| Low | ||
| Average | ||
| Humidity (%) | Actual | |
| Average Humidity | ||
| Wind (mph) Wind (kt) Wind (km/h) | Actual | |
| Max Wind Speed | ||
| Max Wind Gust | ||
| Visibility | ||
| Pressure (in) | Actual | |
| Average Pressure | ||
| Astronomy | Day Length | Rise / Set |
| Actual Time | 14h 15m | 5:40 AM / 7:56 PM |
| Civil Twilight | 5:11 AM / 8:25 PM | |
| Nautical Twilight | 4:33 AM / 9:03 PM | |
| Astronomical Twilight | 3:51 AM / 9:45 PM | |
| Moon: Waning Gibbous | ||
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.