Philadelphia rolled out of bed Tuesday, April 21, 2026, to crystal-clear skies, a bite in the air, and thermometers stuck in the mid‑30s — around 36°F — with a Freeze Warning locked in through 9:00 a.m. EDT. It is a cold start, but forecasters say patience will pay off as sunshine helps temperatures climb into the upper 50s by mid to late afternoon.
Freeze Warning And Marine Advisory
The National Weather Service is flagging pockets of frost and locally sub‑freezing temperatures across parts of the region early this morning, with the Freeze Warning in place until 9:00 a.m. EDT on Tuesday, April 21, 2026. Gardeners and anyone with exposed plumbing are urged to take precautions, according to National Weather Service Mount Holly.
That same briefing also calls out a Small Craft Advisory for Delaware Bay and portions of the Atlantic coastal waters early Wednesday. Forecasters are eyeing gusty south winds and seas in the 2–4 foot range, roughly from 2:00 a.m. to 8:00 a.m. EDT on the bay and 2:00 a.m. to 11:00 a.m. EDT along the oceanfront.
Afternoon, Tonight And The Commute
Once the morning chill eases, Tuesday shapes up as mostly sunny with a high near 58°F and a light west breeze around 5 mph that gradually turns more southerly tonight. After sunset, clouds start to build in, and a chance of rain showers develops after about 11:00 p.m. Overnight lows hover near 46°F, with a few quick, spotty showers possible heading into the Wednesday morning commute.
Looking Ahead
Temperatures bounce back later this week, with highs in the 60s and 70s on tap. Thursday could top out near 75°F before a cooler, wetter pattern edges in for the weekend, when more widespread showers look increasingly likely. For background on the overnight freeze and practical tips for shielding plants and pipes, check out our earlier April 20, 2026 coverage on the overnight freeze and weekday chill.
