The Front Range kicks off October with a stretch of warm, dry weather—perfect for leaf peeping and outdoor plans. After a brief chance of storms on Monday, highs climb into the 80s by midweek under mostly sunny skies. But this unseasonable warmth and sunshine won’t last forever: a late-week system could bring cooler temps and a renewed shot at rain or even Mountain snow. Read on for all the details.
This week’s highlights include:
🌦️ Monday’s brief shower chance: A weak disturbance will spark scattered afternoon and evening showers from the Mountains to the Plains, but limited instability means light rain totals—just a few hundredths to a tenth of an inch.
🌤️ Midweek sunshine and warmth: After Monday, expect mostly dry and sunny conditions through Friday, with highs climbing from the upper 70s Tuesday to low-to-mid 80s by late-week—about 10° above average for early October.
🌬️ Wave clouds possible: Mid and high clouds may drift through Tuesday and Wednesday, with potential for scenic wave clouds over the Foothills and Flatirons.
🌡️ Weekend pattern shift?: A late-week trough should bring cooler temps and a chance of showers or Mountain snow by Saturday, but model guidance is still uncertain.
🍂 October arrives with classic Front Range feels: Crisp mornings, golden foliage, and bluebird skies make this our favorite time of year!
DISCLAIMER: This weekly outlook forecast is created Monday morning and covers the entire upcoming week. Accuracy will decrease as the week progresses as this post is NOT updated. To receive daily updated forecasts from our team, among many other perks, subscribe to BoulderCAST Premium.
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A mellow transition to October across the Front Range
It’s shaping up to be a relatively quiet week weather-wise for Boulder and the surrounding Front Range. Monday brings our only real shot at showers, thanks to a weak west-southwest disturbance sliding through Colorado. There’s just enough moisture and lift in the mid-levels to spark some scattered showers from the Mountains to the Foothills and out onto the Plains—mainly from afternoon into early evening.
The latest HRRR guidance does pick up on this activity, but with limited instability and shear, we’re not expecting anything strong. Rainfall totals will be modest—think a few hundredths to maybe a tenth of an inch in spots. Definitely not a soaking.
Thickening clouds and those rain chances will keep Monday’s highs in the mid-70s, a touch cooler than recent days. The chance of showers or weak thunderstorms on Monday is about 30%, mainly in the window from 2PM to 9PM.
As we close out September and roll into October, the pattern flips toward warmth and dryness. A deep trough digs into the Pacific Northwest midweek, and while it won’t impact us immediately, it’s worth watching for the weekend. Meanwhile, a ridge of high pressure sets up to our south, helping funnel in warmer air across Colorado.
Tuesday and Wednesday may feature some mid and high clouds—especially those classic wave clouds we often see over the Flatirons when the flow is just right. But overall, sunshine dominates from Tuesday through at least midday Friday. Expect highs in the upper 70s Tuesday, climbing into the low 80s Wednesday through Friday. Some spots—especially lower elevations east of Boulder—could flirt with the mid-80s late in the week. That’s about 10 degrees above average for early October, when normally our highs start to dip into the lower 70s. Autumn’s progression is subtle but steady this time of year.
Weekend wildcard: watching a late-week system
Looking ahead to Friday and Saturday, things get a bit more uncertain. There’s potential for a trough and frontal system to move in from the West Coast, but models aren’t in agreement on timing or strength. The GFS (below) hints at a fairly robust shortwave swinging through early Saturday, which could bring a mix of impacts. If that scenario plays out, we might see some snow in the Mountains west of the Divide—especially on peaks favored by westerly upslope—and a few showers for the Boulder-Denver Metro area. However, downslope flow here could limit rain chances locally.
This system could also knock temperatures back toward seasonal norms to start the weekend. We’ll keep a close eye on how things evolve and provide updates through the week as confidence grows.
Right now, most guidance suggests that any rain chances would be delayed until Friday night or Saturday, with warm and dry weather holding on through most or all of Friday. It’s hard to believe this is our five-day forecast heading into October:
With crisp mornings, golden cottonwoods, those iconic bluebird skies and the ever-present threat of our first snow, October is personally our favorite month of the year in Boulder. Whether you’re hiking Chautauqua, traversing the Boulder Creek path, or just soaking up the sunshine, this week’s weather in general should cooperate nicely with any and all outdoor activities. Stay tuned for updates on that weekend system—and enjoy the mellow start to October!
P.S. It’s that magical time of year again! Check back later this week to submit your guess for our 2025 First Snow Contest — entries will go live in the coming days!
Forecast Specifics:
Monday: Partly to mostly cloudy with pockets of scattered showers and a few storms during the afternoon and evening. Light rainfall totals of a tenth of an inch or less. Highs in the mid to upper 70s on the Plains and middle 60s in the Foothills.
Tuesday: Mostly sunny, with a few high clouds later in the day/evening. Highs in the upper 70s on the Plains and upper 60s in the Foothills.
Wednesday: Mostly Sunny and warm with low 80s on the Plains and lower 70s in the Foothills.
Thursday: Sunny and warm with lower 80s for the Plains and lower 70s in the Foothills. A few spots could reach the mid 80s on the Plains.
Friday: Increasing clouds with just a low-end chance of a late-day shower. Highs in the low 80s on the Plains and low 70s in the Foothills.
Weekend: Temperatures are favored to cool off closer to average, along with a potential increased chance of unsettled weather. There could also be some mountain snow early this weekend.
DISCLAIMER: This weekly outlook forecast is created Monday morning and covers the entire upcoming week. Accuracy will decrease as the week progresses as this post is NOT updated. To receive daily updated forecasts from our team, among many other perks, subscribe to BoulderCAST Premium.
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