Severe Thunderstorms Tonight in the Mid-Atlantic; Tropical Storm Bertha in the Gulf

Scattered thunderstorms with severe gusts, hail and a tornado risk are possible near a cold front from the Ohio Valley to the Mid-Atlantic tonight. Tropical Storm Bertha is expected to bring tropical storm conditions to portions of the Gulf Coast from the panhandle of Florida into Louisiana through Wednesday. Read More >

Air Quality

The National Oceanic and Atmospheric Administration (NOAA), in partnership with the Environmental Protection Agency (EPA), issues daily air quality forecast guidance as part of a national Air Quality Forecasting Capability. NOAA's National Weather Service (NWS) currently provides forecast guidance for ozone and smoke based on numerical atmospheric predictions updated twice daily. read more ...

Air Quality Forecast Guidance

Air Quality Alerts (AQA)

Air Quality Indexes (AQI)

About the Air Quality Index

The EPA developed the Air Quality Index (AQI) which reports levels of ozone, particle pollution, and other common air pollutants on the same scale. An AQI reading of 101 corresponds to a level that is above the national air quality standard - the higher the AQI rating, the greater the health impact. The AQI is divided into color-coded categories, and each category is identified by a simple informative descriptor. The descriptors are intended to convey to the public information about how air quality within each category relates to public health.

The table below defines the AQI categories.

AQI	AQI Category	AQI	Color Formulas
Numbers	(Descriptor)	Color	(RGB)	(CMYK)
0 - 50	Good	Green	0,228,0	224,0,224,30
51 - 100	Moderate	Yellow	255,255,0	0,0,255,0
101 - 150	Unhealthy for Sensitive Groups	Orange	255,126,0	0,132,255,0
151 - 200	Unhealthy	Red	255,0,0	0,255,255,0
201 - 300	Very Unhealthy	Purple	153,0,76	0,153,80,102
301 - 500	Hazardous	Maroon	76,0,38	0,76,38,179