The Houston year in pollen
Pollen seasons in Houston: tree pollen December to May, grass March to October, and ragweed from early August until the first frost, around December 28.
First frost lands around December 28 in Houston — about 29 days later than Texas overall — which shifts when ragweed season ends here.
When does ragweed season end in Houston?
Ragweed season in Houston typically ends with the first frost, around December 28. Some years it comes as early as December 10, some as late as January 7.
A light frost around December 28 knocks the season down; the hard freeze that finishes it usually follows by January 8. Based on 30 years of NOAA frost records (1991–2020).
The rest of the Houston pollen year
| Allergen | Typical season |
|---|---|
| Mountain cedar (Ashe juniper) | December to February |
| Oak (live oak) | March to May |
| Elm | February to April |
| Cedar elm (fall) | August to October |
| Pecan | April to May |
| Cottonwood | March to April |
| Grass | March to October |
Season-by-season detail is on the Texas page.
Nearby calendars
Frost dates for Houston come from the Houston Hobby Airport weather station's 30-year records. Season windows reviewed August 2026.