Death Valley is the hottest and driest place in North America due to its lack of surface water and low relief. It is so frequently the hottest spot in the United States that many tabulations of the highest daily temperatures in the country omit Death Valley as a matter of course.
https://en.wikipedia.org/wiki/Death_Valley_National_Park
Ahh, I see you're coming in december. To answer your other question. You easily can spend 3 full days that time of year, but I'd rent a SUV, pref. 4wd for this visit. It gives you the chance to do drive dirtroads like Titus Canyon and others but always check for roadcondition first and don't go too far off road.
https://www.tripadvisor.com/ShowTopic-g143021-i2027-k3100066-Weather_in_December-Death_Valley_National_Park_California.html
* Updated Saturday, April 15, 2017 5:18:51 am Furnace Creek (Death Valley) time - Weather by CustomWeather, © 2017. 14 day forecast, day-by-dayHour-by-hour forecast for next week.
http://www.timeanddate.com/weather/usa/furnace-creek-death-valley
Here is the weather section of the website. You can follow all the links to get historical data on temperatures and precipitation, historic highs, lows, and averages for every day of the year, and current conditions. In December, there can be heavy rains, and snow and ice at higher elevations.
https://www.tripadvisor.com/ShowTopic-g143021-i2027-k3100066-Weather_in_December-Death_Valley_National_Park_California.html
Higher elevations are cooler than the low valley. Temperatures drop 3 to 5°F (2 to 3°C) with every thousand vertical feet (approx. 300m). Sunny skies are the norm in Death Valley, but winter storms and summer monsoons can bring cloud cover and rain. Wind is common in the desert, especially in the spring.
https://www.nps.gov/deva/planyourvisit/weather.htm
Death Valley National Park. Death Valley National Park is a national park in the United States. Straddling the border of California and Nevada, located east of the Sierra Nevada, it occupies an interface zone between the arid Great Basin and Mojave deserts in the United States.
https://en.wikipedia.org/wiki/Death_Valley_National_Park
At 282 feet below sea level, Death Valley is the eighth lowest depression on earth and the deepest in North America. The valley lies 300 miles northwest of Los Angeles, along the eastern flank of the towering Sierra Nevada Range.
http://traveltips.usatoday.com/weather-climate-death-valley-california-59328.html
The depth and shape of Death Valley influence its summer temperatures. The valley is a long, narrow basin 282 feet (86 m) below sea level, yet is walled by high, steep mountain ranges. The clear, dry air and sparse plant cover allow sunlight to heat the desert surface.
https://www.nps.gov/deva/planyourvisit/weather.htm
Average Temperature. Death Valley is the hottest place in North America, according to the National Park Service, with highest temperatures coming in July, when the average is 115 degrees Fahrenheit. Actual highs often top 120 degrees and the record high was 134 degrees in July of 1913.
http://traveltips.usatoday.com/weather-climate-death-valley-california-59328.html
Climate Death Valley - California. °C | °F. Climate data for death valley, Longitude: -116.867, Latitude: 36.4622. Average weather Death Valley, CA - 92328 - 1981-2010 normals. Jan: January, Feb: February, Mar: March, Apr: April, May: May, Jun: June, Jul: July, Aug: August, Sep: September, Oct: October, Nov: November, Dec: December.
http://www.usclimatedata.com/climate/death-valley/california/united-states/usca0286
what is the weather in death valley
The average weather in Death Valley is 115 degrees Fahrenheit. According to the National Park Service, in Death Valley the highest temperatures coming in July, when the average is 115 degrees Fahrenheit.