US pollen season and air quality today

Monday, October 5: SkyPollen does not yet have a pollen level for US cities, so this page does not show one. It is ragweed season: weed pollen usually stays in the air until the first hard frost, which in most of the country comes in October. What we can show is the air itself: the CAMS global model puts today's highest fine-particle level of these metros in Phoenix, at 23 µg/m³ PM2.5 (daily mean, model value).

• Phoenix, AZ
  PM2.5 23 µg/m³ · dust 0.065
• Los Angeles, CA
  PM2.5 15.9 µg/m³ · dust 0.021
• San Francisco, CA
  PM2.5 15.1 µg/m³ · dust 0.009
• Seattle, WA
  PM2.5 14 µg/m³ · dust 0.012
• Philadelphia, PA
  PM2.5 11.5 µg/m³ · dust 0.003
• New York, NY
  PM2.5 10.4 µg/m³ · dust 0.003
• Washington, DC, DC
  PM2.5 9.7 µg/m³ · dust 0.004
• Atlanta, GA
  PM2.5 7.2 µg/m³ · dust 0.003
• Boston, MA
  PM2.5 7.2 µg/m³ · dust 0.004
• Houston, TX
  PM2.5 7 µg/m³ · dust 0.001
• Miami, FL
  PM2.5 6.9 µg/m³ · dust 0
• Chicago, IL
  PM2.5 5.8 µg/m³ · dust 0.003
• Dallas, TX
  PM2.5 5.8 µg/m³ · dust 0.002
• Minneapolis, MN
  PM2.5 5.8 µg/m³ · dust 0.003
• Denver, CO
  PM2.5 4.9 µg/m³ · dust 0.003

Bar length: today's mean PM2.5 against 35.4 µg/m³, the top of the EPA "Moderate" 24-hour range. Model values, not monitor readings.

Copernicus CAMS global forecast run of Oct 4, 8:00 PM EDT, shown as computed. PM2.5 and dust can make allergy and asthma symptoms worse on top of pollen. "Dust" is the dust aerosol optical depth at 550 nm: near 0 is clean air, values above about 0.2 mean noticeable dust. For official readings see AirNow (EPA); for local pollen counts see the AAAAI National Allergy Bureau.

When pollen is in the air in the US

• Trees (oak, maple, birch, cedar)
  Feb – Jun: February to May; mountain cedar in Texas from December
• Grass
  May – Aug: May to July in the North; much of the year in the South
• Ragweed and other weeds
  Aug – Nov: mid-August until the first hard frost, usually October

Axis: January to December. The usual US pattern; local timing shifts with latitude and weather.

Spring is tree pollen (oak, maple, birch, elm, and mountain cedar in Texas in winter), early summer is grass, and late summer to autumn is ragweed. A single ragweed plant can release about a billion pollen grains, and the grains travel hundreds of miles on the wind.

What is coming

A US pollen map in the style of our Australian maps, with pollen drifting from tree and grass sources on the forecast wind, is planned for the spring 2027 tree season. Until it is checked against counts, no level will be shown.