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 | 47 °F 46.9 °F 8 °C 8.3 °C | 62 % | NNE | 14 mph 12 kt 22 km/h | 22 mph 19 kt 35 km/h | 29.84 in | 0.0 in | Fair |
| METAR KMDW 130553Z 03012G19KT 10SM FEW070 16/08 A2984 RMK AO2 SLP099 T01560083 10189 20156 402330067 53016 | |||||||||
| 1:53 AM | 57 °F 57 °F 14 °C 13.9 °C | 46 °F 46 °F 8 °C 7.8 °C | 67 % | NE | 8 mph 7 kt 13 km/h | 0 mph 0 kt 0 km/h | 29.85 in | 0.0 in | Mostly Cloudy |
| METAR KMDW 130653Z 04007KT 10SM BKN060 14/08 A2985 RMK AO2 WSHFT 0541 SLP102 T01390078 | |||||||||
| 2:53 AM | 55 °F 55 °F 13 °C 12.8 °C | 44 °F 44.1 °F 7 °C 6.7 °C | 66 % | NE | 4 mph 3 kt 6 km/h | 0 mph 0 kt 0 km/h | 29.85 in | 0.0 in | Mostly Cloudy |
| METAR KMDW 130753Z 04003KT 10SM BKN050 BKN065 13/07 A2985 RMK AO2 SLP104 T01280067 | |||||||||
| 3:53 AM | 55 °F 55 °F 13 °C 12.8 °C | 43 °F 43 °F 6 °C 6.1 °C | 64 % | N | 0 mph 0 kt 0 km/h | 0 mph 0 kt 0 km/h | 29.86 in | 0.0 in | Mostly Cloudy |
| METAR KMDW 130853Z 00000KT 10SM BKN048 BKN065 13/06 A2986 RMK AO2 SLP106 T01280061 51006 | |||||||||
| 4:53 AM | 55 °F 55 °F 13 °C 12.8 °C | 43 °F 43 °F 6 °C 6.1 °C | 64 % | N | 0 mph 0 kt 0 km/h | 0 mph 0 kt 0 km/h | 29.86 in | 0.0 in | Mostly Cloudy |
| METAR KMDW 130953Z 00000KT 10SM BKN046 BKN070 13/06 A2986 RMK AO2 SLP109 T01280061 | |||||||||
| 5:53 AM | 55 °F 55 °F 13 °C 12.8 °C | 44 °F 44.1 °F 7 °C 6.7 °C | 66 % | NNW | 5 mph 4 kt 7 km/h | 0 mph 0 kt 0 km/h | 29.89 in | 0.0 in | Mostly Cloudy |
| METAR KMDW 131053Z 33004KT 10SM BKN037 BKN055 BKN075 13/07 A2989 RMK AO2 SLP118 T01280067 | |||||||||
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 32m | 5:31 AM / 8:03 PM |
| Civil Twilight | 5:01 AM / 8:33 PM | |
| Nautical Twilight | 4:21 AM / 9:12 PM | |
| Astronomical Twilight | 3:37 AM / 9:57 PM | |
| Moon: Waning Crescent | ||
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.