Tucson weather in December

Tucson-forum threads on summer weather call July genuinely brutal by mid-morning, highs regularly right around the 100F mark, and posters are direct that this is also when the monsoon kicks in, humidity climbing alongside the heat rather than offsetting it. The daily pattern regulars describe is a clear, building morning followed by a genuine afternoon or evening thunderstorm, sometimes dramatic enough to flood a low-lying road for an hour, then clearing fast. Standing advice across every thread is an early start for any outdoor activity, real hydration throughout the day, and treating midday as strictly indoor or pool time. Regulars call Tucson noticeably more bearable than nearby Phoenix thanks to the elevation, but still not a month for an ambitious hiking itinerary. The record: a scorching 39.9C by day feeling like a punishing 40C, 26.2C nights, 71mm across 8.1 days, a dry 40 percent humidity and 12.3 hours of sun.

Tucson's forum is enthusiastic about October, calling it close to the ideal month once monsoon season has wrapped up and the desert dries back out. Regulars describe warm but not hot afternoon highs in the low-to-mid 80s (peaking around 2-3pm), minimal wind, and a big day-to-night swing - a typical early evening in the low 70s can drop to the 50s by early morning. The consensus across threads was that hiking and general sightseeing conditions in both the mountains and the desert floor are about as good as Tucson gets this time of year.

Forum posters describe May, especially its second half, as extremely hot, dry and sunny ahead of the summer monsoon, with daytime highs commonly in the mid-to-high 90sF and occasionally topping 100F, nights still dropping into the mid-60sF, and humidity under 10% making it one of the driest stretches of the year. Posters recommend timing outdoor activities like Saguaro National Park for sunrise, since midday heat makes exploring either side of the park genuinely uncomfortable, with the Arizona-Sonora Desert Museum a good option right at opening. Posters also suggest a drive up Mount Lemmon to Summerhaven as a reliable way to find cooler air without leaving the area. Posters generally rate May as hot and bone-dry but manageable with early starts and elevation escapes built into the day.

Forum posters describe September in Tucson as still capable of hitting 100F, with daytime temperatures commonly in the 90s-to-100 range persisting into October, though posters consistently emphasize that the region's dry heat makes it more bearable than the number alone suggests. Posters describe the June-15-through-September-15 monsoon season as typically bringing quick-moving late-afternoon thunderstorms, not an all-day soak, with rising humidity from around early July through August or early September before the rains begin to taper off. Posters consistently recommend scheduling outdoor activities for early morning given the intense afternoon heat. Posters generally rate September as a transitional month, still genuinely hot but with the monsoon winding down and more comfortable fall weather starting to take hold by month's end.