Apps and tools
The pages here answer one question well: whether a given night at one of these places is worth the drive. They do not name the bright point over the ridge, plan a photograph, forecast the steadiness of the air, or say when the space station passes. The tools below do, and each is listed with what it is bad at as well as what it is for.
Naming what is up there
A planetarium app draws the sky for wherever the phone is pointed, which settles most of the arguments at a pullout. Stellarium is the free, open-source one for a computer, on Windows, Mac and Linux, with a default catalog of over 600,000 stars, and its site links a browser version, Stellarium Web, for when there is no install to be had. Its mobile version, Stellarium Mobile, comes from the original creator and carries the Gaia catalog of over 1.4 billion stars in the app itself; the Plus upgrade adds telescope control, an ocular view, observation planning, a calendar of events and satellite passes, and 3D views. SkySafari 8 is the serious one for people with a telescope, sold in Basic, Plus and Pro editions on iOS and Android; the Pro edition carries its largest databases and the plate solving that matches a photograph to the chart. Star Walk 2 is a real-time sky map on the phone's screen with an encyclopedia of the sky behind it.
What none of them does is forecast. A planetarium app will draw a perfect sky over a night of solid cloud. And any of them at full white brightness undoes twenty minutes of dark adaptation in a second, which is what the last section on this page is for.
Planning a photograph
PhotoPills, a paid app for iPhone and iPad by its App Store listing, plans the sun, the moon and the Milky Way over a chosen spot and carries the calculators the photography page describes, Spot Stars for the exposure limit and Star Trails among them. Planit! does the same planning with a simulated viewfinder that lays the ephemeris over a map, a photograph or a street view, on Android and iOS. Both are dense, and both take an evening at the kitchen table before they earn their keep in the dark; neither replaces standing at the pullout the evening before to see where the ridge really is.
Weather for astronomers beyond these places
The forecast here scores cloud, moon and darkness for these places and says why. Clear Outside, from First Light Optics in the UK, gives a seven-day hourly forecast for any latitude and longitude, cloud by layer, visibility, fog, wind, temperature and dew point, designed in its own words by astronomers for astronomers, with free iOS and Android apps. Astrospheric is for North American astronomers, by its own description, and goes further on two things this site does not forecast at all: the steadiness of the air, called seeing, which is what matters for planets and telescopes, with hourly figures from Allan Rahill's model, and a transparency forecast that includes wildfire smoke. It names the weather models it draws on at the foot of every forecast, and its Professional tier is paid.
How dark it is where you are going
Light pollution map, at lightpollutionmap.info, draws the light the ground sends upward from NASA's Black Marble satellite data year by year, the modeled sky brightness of the World Atlas of 2015, and, where someone has stood there with a meter, their contributed readings, with cloud and aurora overlays on top. What it shows is a satellite's view of light leaving the ground and a model built from it, not a measurement of the sky over any one pullout, and the World Atlas figures are a decade old; it is the right way to compare two regions and the wrong way to publish a number for a place, which is why this site publishes none it has not measured.
Aurora
The aurora page here reads the feeds of NOAA's Space Weather Prediction Center and shows the three-day forecast, the solar wind arriving at the moment, and what the northern horizon at each place does to the odds. Those feeds are public, and an app that sends a push notification is a convenience laid over numbers anyone can read there.
The station overhead
The International Space Station crosses the sky looking, in NASA's words, like an airplane or a very bright star, moving steadily and without blinking, and it is easy to miss for want of knowing when. Spot the Station is NASA's own app: it tracks the station in real time and sends a notification when a viewing pass is due over the phone's location.
A red screen
Every page on this site has a red-light mode, the toggle at the top, because a white screen at a dark site costs twenty minutes of dark adaptation. The phone itself can do the same for every app on it. On an iPhone, Apple's guide puts it under Settings, Accessibility, Display and Text Size, Color Filters, where a tint of a chosen color covers the whole screen with a slider for how deep.
What this page is not
None of these links pays the site. There are no affiliate links or referral codes here, and no app or maker has been asked for anything or offered anything. No price is written here, because prices live on the stores and change without notice.