Today | Weather | Wednesday, May 20, 2026

Active Weather Warnings

Severe Thunderstorm Watch

Weather in Lancaster, Pennsylvania

05:51 PM

Now

79° F

Feels Like 75°

Precipitation 85 %

Wind 7 mph

UV Index (0 - 11+) 1

Humidity 63 %

Today

Day 90°

Night 57°

Precipitation 89 %

Wind 8 mph

UV Index (0 - 11+) 10

Warning: High UV Index Today: 10

High risk of harm from unprotected sun exposure. Take precautions: wear a hat, sunglasses, and apply sunscreen regularly if you’ll be outdoors for extended periods.

Lancaster Weather Forecast Updated

6 minutes ago

Last updated on May 20, 2026 at 5:45 PM

Weather Forecast History

Last Year's Weather on This Day (May 20, 2025)

Day

66°

Night

45°

Air Quality in Lancaster

NOW

34 AQI

Good air quality Dominant pollutant: O₃

Pollutant Concentrations:

PM_2.5 3.35 µg/m³

PM₁₀ 4.14 µg/m³

O₃ 0.037 ppm

NO₂ 6.9 ppb

SO₂ 0.9 ppb

CO 0.14 ppm

NH₃ 1.17 µg/m³

NO 0.21 µg/m³

PM_2.5 – Fine particles <2.5μm

PM₁₀ – Inhalable particles <10μm

O₃ – Ozone

NO₂ – Nitrogen dioxide

SO₂ – Sulfur dioxide

CO – Carbon monoxide

NH₃ – Ammonia

NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)

PM_2.5 – 3.35 µg/m³

PM₁₀ – 4.14 µg/m³

O₃ – 72.42 µg/m³

NO₂ – 13.06 µg/m³

SO₂ – 2.25 µg/m³

CO – 162.53 µg/m³

NH₃ – 1.17 µg/m³

NO – 0.21 µg/m³

View Hourly Air Quality Forecast

Weather Alerts and Warnings for Lancaster

Severe Future Possible

Severe Thunderstorm Watch

Severe Thunderstorm Watch issued May 20 at 12:40PM EDT until May 20 at 8:00PM EDT by NWS State College PA

May 20, 12:40 PM → May 20, 8:00 PM

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH
234 IN EFFECT UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING AREAS

IN PENNSYLVANIA THIS WATCH INCLUDES 18 COUNTIES

IN CENTRAL PENNSYLVANIA

ADAMS BEDFORD COLUMBIA
CUMBERLAND DAUPHIN FRANKLIN
FULTON HUNTINGDON JUNIATA
LANCASTER LEBANON MIFFLIN
NORTHUMBERLAND PERRY SCHUYLKILL
SNYDER SOMERSET YORK

THIS INCLUDES THE CITIES OF BEDFORD, BERWICK, BLOOMSBURG,
CARLISLE, CHAMBERSBURG, GETTYSBURG, HARRISBURG, HERSHEY,
HUNTINGDON, LANCASTER, LEBANON, LEWISTOWN, MCCONNELLSBURG,
MIFFLINTOWN, MOUNT UNION, NEWPORT, POTTSVILLE, SELINSGROVE,
SHAMOKIN, SOMERSET, SUNBURY, WAYNESBORO, AND YORK.

Updated: May 20, 3:53 PM Source: NWS Alert