The darker period of the year lasts for 3.4 months, from November 2 to February 13, with an average daily incident shortwave energy per square meter below 2.6 kWh. 1974. The windiest day of the year is January 15, with an average hourly wind speed of 12.8 miles per hour. From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night. We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. The tourism score favors clear, rainless days with perceived temperatures between 65Â°F and 80Â°F. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. We report snowfall in liquid-equivalent terms. Daylight saving time (DST) is observed in Ann Arbor during 2020, starting in the spring on March 8, lasting 7.8 months, and ending in the fall on November 1. The estimated value at Ann Arbor is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Ann Arbor and a given station. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day. The chance of a wet day peaks at 35% on June 14. The drier season lasts 5.6 months, from October 7 to March 27. The stations contributing to this reconstruction are: Willow Run Airport (54%, 18 kilometers, east); Livingston County Spencer J. Hardy Airport (14%, 44 kilometers, northwest); Oakland County International Airport (12%, 51 kilometers, northeast); Lenawee County Airport (11%, 53 kilometers, southwest); and Jackson County Airport (9%, 60 kilometers, west). Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more. The figure below presents a compact representation of key lunar data for 2020. The hottest day of the year is July 18, with an average high of 84Â°F and low of 63Â°F. Based on weather reports collected during 1985–2015. The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands. The average hourly temperature, color coded into bands. Most days of snowfall in Ann Arbor result in just a skiff of less than an inch of fresh snow left on the ground. Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations. The average annual temperature is 8.7 °C | 47.7 °F in Ann Arbor. A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation.