In article opr2gh0ekss5tvhu@news-server, Lawrence Sayre wrote:
Can anyone point me to a website which lists the average number of clear
days (nights would be even better) per year for cities across the USA?

Lawrence Sayre

There's summary data for lots of US cities -- monthly percentages of
clear/partly-cloudy/cloudy days (sunrise-to-sunset, unfortunately) -- at

http://ols.nndc.noaa.gov/plolstore/p....prodspecific?
prodnum=C00095-PUB-A0001

[you'll need to paste the above URL back together -- no space between
the "prodspecific?" and "prodnum=C00095-PUB-A0001"]

This comes from following the sequence
NOAA online store
http://ols.nndc.noaa.gov/plolstore/p...re.main?look=1

select Climate - Data, Cloud, and hit Continue for list

select Comparative Climatic Data
select Cloudiness - Mean Number of Days (Clear, Partly Cloudy, Cloudy)


A few years ago NOAA offered lots of raw individual-station data for free,
but not any more. For more detailed data you can buy on-line a time-series
hourly observations, including cloud cover, for lots of sites across
the US for $2.00 per site. There's also a CD of hourly observations
for 262 sites, spanning 1990-1995, for $130.00; and three regional CDs
(Western/Central/Eastern) spanning 1961-1990, for $130.00 per CD.

And, for $50 there's a "Climate Atlas of the United States" CD,
spanning mostly 1961-1990. It appears to include daytime cloud cover data.
Not sure whether it offers time-series data (month-by-month or year-by-year)
or only mean&extreme values over the period. Anyway it's described at:
http://ols.nndc.noaa.gov/plolstore/p....prodspecific?
prodnum=C00519-CDR-A0001
[likewise, paste the above two lines together]


There may well be lots of other data sources available. The above just came
from following a link I'd bookmarked a few years ago, which now redirects
to the NOAA on-line store.

Guy Ottewell's "Astronomical Companion" (a wonderful book, not a website)
includes seasonal cloudiness contour maps for the continental US.

Stuart