Other Useful Weather Data

The Hottest City widget on this page compares live temperatures across roughly 65 major US cities and names the current leader with its temperature. In summer the hottest reading is usually in the Desert Southwest — Phoenix, Las Vegas, or Death Valley's nearby stations — while in winter it more often shifts to South Florida or South Texas.

The Moon Phase widget on this page calculates tonight's phase and illumination percentage from the synodic month of 29.53 days, referenced to the new moon of January 6, 2000. It renders the actual lit fraction of the disc rather than a generic icon, so the shape you see matches what is visible in the sky.

Dew point measures the absolute amount of moisture in the air, while relative humidity only describes how close the air is to saturation at its current temperature — so a cold morning can hit 100 percent humidity and still feel dry. Dew points below 55°F feel comfortable, 60–65°F feels noticeably humid, above 70°F feels oppressive, and above 75°F is tropical.

The solar terminator is the moving line separating the sunlit half of Earth from the half in darkness. The day/night map on this page computes it from the sun's current declination and Greenwich hour angle, showing exactly which parts of the world are in daylight at this moment.