Election and post election day were in almost whole territory of the USA associated with warm and sunny weather, what should have impact on results of elections.
Mainly weather on Wednesday, 4. November brought extremely warm and sunny weather in large part of US territory - mainly in West, Central, Northern USA and Midwest. On Thursday, 5. November, unseasonably high November temperatures has shifted over Northeast, too.
According to researches, calm, sunny, warm and not rainy and humid weather is linked with higher election participation of "potential voters". Potential voters are voters with weaker sense for civil duties, which often going to vote during nice weather, while when weather is bad, he/she doesn´t participate.
It means, that in states with strong Indian summer conditions, a lot of Trump´s voters went to vote (e.g. Nebraska, where it was measured on Wednesday recorded 82°F / +27,8°C in North Platte - see animation below with regions with temperature records), while in eastern regions, where wasn´t so warm and sunny, yet, Biden should prefer from this synoptic situation.
From measured maximum temperatures on Wednesday, 4. November 2020 were interesting e.g.: Northern Platte, Nebraska, +27,8°C, Goodland, Kansas, +26,1°C, Denver, Colorado, +24,4°C, Rapid City, South Dakota, +24,4°C, Alpena, Michigan, +23,3°C, Chicago, Illinois,+23,3°C, International Falls, Minnesota, +23,3°C, Sioux Falls, South Dakota, +23,3°C, Billings, Motnana, +22,2°C, Indianapolis, Indiana, +21,7°C, Detroit, Michigan, +21,1°C, Cleveland, Ohio, +20,6°C, Baltimore, Maryland, +20,0°C and Minneapolis, Minnesota, +20,0°C.
On Thursday, 5. November 2020, maximum temperatures has reached September´s values e.g. in Rapid City, South Dakota, +23,3°C, Denver, Colorado, +22,8°C, Baltimore, Maryland, +21,1°C, Cleveland, Ohio, +21,1°C, Boston, Massachusetts, +20,6°C, Chicago, Illinois, +20,6°C, New York, NY, +20,6°C, Cheyenne, Wyoming, +20,0°C, Great Falls, Montana, +20,0°C, Helena, Montana, +20,0°C, Philadelphia, Pensylvania, +20,0°C and Pittsburgh, Pensylvania, +20,0°C.
In all cities above, temperature has reached both days values between 68°F - 82°F.
Correlation of voter turnout with precipitation from Sweden (Persson et al., 2014) PERSSON, M., SUNDELL A., OHRVALL R., Does Election Day weather affect voter turnout? Evidence from Swedish elections. Electoral Studies 33: 335 342.