It's a chilly morning in Tucson, with low temperatures having dropped into the low-40s. PM10 (dust) levels are also low, thanks to yesterday's rain. Davis-Monthan Air Force Base logged in 0.39" of rain. But much of the Tucson area saw more than half an inch.

Looking ahead, daytime temperatures this week will fluctuate based on the weather pattern over Arizona. Today through Wednesday, highs will be on a gradual incline as high pressure builds behind this weekend's weather system. Wednesday will be the warmest day, with highs in the low-70s. Then by Thursday, temperatures will drop again as another low-pressure wave extends over the state. Thursday and Friday will see highs in the low to mid 60s.

However, through all of this, overnight temperatures will retain their chilliness (Thursday could see lows dip into the 30s). As such, PM2.5 (smoke) will be the pollutant to watch. For one, PM2.5 rebounds quicker from rain than PM10 (dust) does. Two, colder temperatures mean increased fireplace usage. And finally, colder temperatures result in stronger nighttime inversions, which trap PM2.5 near the ground.

Overall, we can't rule out Moderate PM2.5 levels this week. If you're sensitive to PM2.5, afternoons will be the best time of day to be outside. PM10 and ozone will remain in the Good AQI category.

Check back tomorrow morning for the latest!

- M. Graves
ADEQ Meteorologist