KMDW — CHICAGO
Chicago, IL, US · America/Chicago · 41.7860°, -87.7524° · 188m elevation
Daily METAR Observations
| Time | Temperature | Dew Point | Humidity | Wind | Wind Speed | Wind Gust | Pressure | Precip. | Condition |
|---|---|---|---|---|---|---|---|---|---|
| 12:53 AM | 60 °F 60.1 °F 16 °C 15.6 °C | 48 °F 48 °F 9 °C 8.9 °C | 64 % | WNW | 6 mph 5 kt 9 km/h | 0 mph 0 kt 0 km/h | 29.60 in | 0.0 in | Partly Cloudy |
| METAR KMDW 050553Z 30005KT 10SM SCT100 SCT250 16/09 A2960 RMK AO2 SLP016 60001 T01560089 10183 20139 402720094 53019 | |||||||||
| 1:53 AM | 59 °F 59 °F 15 °C 15 °C | 38 °F 37.9 °F 3 °C 3.3 °C | 45 % | NW | 6 mph 5 kt 9 km/h | 0 mph 0 kt 0 km/h | 29.61 in | 0.0 in | Partly Cloudy |
| METAR KMDW 050653Z 31005KT 10SM SCT110 SCT250 15/03 A2961 RMK AO2 SLP020 T01500033 | |||||||||
| 2:53 AM | 59 °F 59 °F 15 °C 15 °C | 32 °F 32 °F 0 °C 0 °C | 36 % | NW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 29.63 in | 0.0 in | Overcast |
| METAR KMDW 050753Z 32009KT 10SM OVC100 15/00 A2963 RMK AO2 SLP027 T01500000 | |||||||||
| 3:53 AM | 58 °F 57.9 °F 14 °C 14.4 °C | 33 °F 33.1 °F 1 °C 0.6 °C | 39 % | NW | 8 mph 7 kt 13 km/h | 0 mph 0 kt 0 km/h | 29.68 in | 0.0 in | Overcast |
| METAR KMDW 050853Z 32007KT 10SM OVC100 14/01 A2968 RMK AO2 SLP043 T01440006 53028 | |||||||||
| 4:53 AM | 55 °F 55 °F 13 °C 12.8 °C | 34 °F 34 °F 1 °C 1.1 °C | 45 % | NW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 29.71 in | 0.01 in | Overcast |
| METAR KMDW 050953Z 32009KT 10SM OVC090 13/01 A2971 RMK AO2 RAB22E33 SLP053 P0000 T01280011 | |||||||||
| 5:53 AM | 53 °F 53.1 °F 12 °C 11.7 °C | 33 °F 33.1 °F 1 °C 0.6 °C | 46 % | NNW | 10 mph 9 kt 17 km/h | 0 mph 0 kt 0 km/h | 29.72 in | 0.01 in | Overcast |
| METAR KMDW 051053Z 33009KT 10SM FEW060 OVC100 12/01 A2972 RMK AO2 RAB34E45 SLP060 P0000 T01170006 | |||||||||
| 6:53 AM | 51 °F 51.1 °F 11 °C 10.6 °C | 31 °F 30.9 °F -1 °C -0.6 °C | 46 % | NNW | 12 mph 10 kt 19 km/h | 0 mph 0 kt 0 km/h | 29.76 in | 0.01 in | Light Rain |
| METAR KMDW 051153Z 33010KT 10SM -RA BKN060 OVC090 11/M01 A2976 RMK AO2 RAB52 SLP076 P0000 60000 70007 T01061006 10156 20106 53028 | |||||||||
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 14m | 5:40 AM / 7:55 PM |
| Civil Twilight | 5:11 AM / 8:24 PM | |
| Nautical Twilight | 4:33 AM / 9:02 PM | |
| Astronomical Twilight | 3:51 AM / 9:43 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.