Submit feedbackSubmit feedbackComplete travel information for your September journey
In September, early morning flights (5–8 AM) and late evening departures (8–11 PM) from San Francisco International Airport (SFO) to Denver International Airport (DEN) typically have lower fares and fewer delays. Shoulder-season travel in September often reduces crowds at SFO, and you can find better availability on nonpeak days midweek. Book 3–6 weeks in advance for the best combination of price and choice.
A nonstop flight from San Francisco International Airport (SFO) to Denver International Airport (DEN) typically takes about 2 hours and 20 minutes to 2 hours and 40 minutes depending on winds and routing. Scheduled block times used by airlines usually list around 2h30m for planning. Always check the specific flight duration when booking for real-time schedule and connection planning.
Yes, several carriers operate daily nonstop flights from San Francisco International Airport (SFO) to Denver International Airport (DEN) throughout September, with multiple morning and evening options. Major carriers such as United Airlines, Southwest Airlines, and Alaska Airlines typically offer nonstop service, though frequencies may vary on weekends and holidays. Check airline schedules and book early to lock in nonstop seats during popular September weekends.
As of September, most domestic flights from San Francisco International Airport (SFO) follow standard TSA and airline health guidance; specific COVID-19 travel mandates are rare but can change by jurisdiction. Travelers should verify airline mask policies, carry proof of vaccination if required by final destination, and monitor local San Francisco and Colorado health advisories before travel. For the latest rules, check SFO's official website and your airline's travel advisories prior to departure.
For a domestic SFO to DEN flight in September, arrive at least 90 minutes before departure for standard checked luggage and 2 hours if you need extra help, TSA PreCheck enrollment, or during holiday weekends. San Francisco International Airport can have longer security lines during peak commuter hours (weekday mornings), so add extra buffer if traveling with family or oversized baggage. Use real-time airport security wait trackers or your airline app to adjust arrival time.
September generally offers stable fall weather for departures at San Francisco International Airport (SFO), but you should be aware that Denver can experience sudden temperature swings and early-season mountain storms that affect arrivals at Denver International Airport (DEN). Turbulence is possible when crossing the Sierra and Rockies, so check forecasts and consider travel insurance for schedule disruptions during seasonal transitions. Pack layers and plan for airport delays if weather systems are active over the Rockies.
From Denver International Airport (DEN) to downtown Denver, the RTD A Line commuter train, ride-shares, shuttles, and rental cars are the most common options in September. The A Line provides a reliable 37-minute link to Union Station, while ride-shares are convenient for late arrivals or groups. During September events like the Great American Beer Festival, expect higher demand for rides and plan transfers in advance.
Denver International Airport (DEN) has centralized baggage claim and a large on-site car rental center accessible by free shuttle or transit. In September, car rental demand can spike around festivals and sports events, so reserve vehicles early and confirm pick-up hours. For baggage, use the airline app to track your bag and allow extra time if your flight arrives during peak afternoon periods.
Arriving at Denver International Airport (DEN), which sits over 5,400 feet above sea level, can cause mild altitude effects such as shortness of breath and dehydration—common in September as temperatures are moderate but air is dry. Stay hydrated, limit strenuous activity on your first day, and consult a physician if you have heart or respiratory conditions. There are no routine entry health restrictions for domestic flights, but check event-specific advisories.
From Denver International Airport (DEN) you can access top Colorado destinations like Boulder, Colorado Springs, Fort Collins, Vail, Aspen, and Rocky Mountain National Park. September is ideal for scenic drives and leaf-peeping in mountain towns as early fall colors begin at higher elevations. Ground transportation options and regional shuttles to resort areas increase in September for weekend travelers.
Denver International Airport (DEN) sees moderate crowds in September, with spikes during event weekends and Broncos home games; early fall travel is generally less congested than summer. Allow extra time for baggage claim and ground transportation during high-demand periods. Use airline apps and airport monitors to track arrival gates and luggage status for a smoother experience.
Denver International Airport (DEN) offers a range of lounges, dining options, and retail shops across concourses, ideal for arrivals and layovers in September. Lounges provide comfortable spaces to rest and recharge before connecting to mountain destinations; check access rules and hours as they may vary with airline contracts. For families, there are play areas and family restrooms to ease post-flight transitions.
The Great American Beer Festival in late September is one of Denver's largest events and often increases flight and hotel demand at Denver International Airport (DEN). Other September happenings include local fall fairs, arts festivals, and college football games that can raise weekend fares and ground transportation demand. If your travel overlaps with major Denver events, book flights and airport transfers early, and consider arriving a day earlier to avoid same-day travel congestion. CTA: Check Denver event dates and secure your SFO to DEN flight and transfer for September now.
The best time to fly SFO to DEN in September is midweek (Tuesday–Thursday) and during early morning or late evening time slots to avoid commuter peaks and secure lower fares. Early September after Labor Day often yields the best deals, while late September may see price increases around Denver events like the Great American Beer Festival. For business travelers, mid-morning flights reduce the risk of early-morning delays; leisure travelers may prefer weekend departures but should book early to avoid premium pricing. CTA: Compare midweek September fares now to find the best combination of price and convenience.
Nonstop flights from San Francisco International Airport (SFO) to Denver International Airport (DEN) in September save time — usually shaving 60–120 minutes off a connecting itinerary — and reduce the risk of missed connections. Connecting flights can be cheaper, especially if you’re flexible with travel times or using smaller carriers, but they increase the chance of delays, baggage mishandling, and longer travel days. If your priority is speed and convenience for short trips in September, choose nonstop options; for lower fares or specific loyalty routing, consider one-stop itineraries with reliable carriers. CTA: Filter your search for nonstop SFO to DEN flights to compare prices and durations.
United Airlines: Strong presence with multiple daily nonstop flights between San Francisco International Airport (SFO) and Denver International Airport (DEN), good for mileage program members and business travelers. Southwest Airlines: Competitive fares and generous free checked bags, often offering low fares for September, ideal for families and cost-conscious travelers. Alaska Airlines: Reliable service and good customer satisfaction, with competitive nonstops and connections through their West Coast network. Compare seat selection fees, change fees, and loyalty benefits when booking — the cheapest carrier may not be the best value once baggage and seat fees are included. CTA: Compare SFO to DEN flight prices across airlines for your September dates and select the best balance of price and perks.
Pack layers for September travel: mornings and evenings in Denver can be cool, while daytime temperatures may be warm. Stay hydrated to mitigate altitude effects upon arrival at Denver International Airport (DEN), and avoid intense exercise your first day. Check airline baggage policies before you pack and reserve rental cars ahead of peak festival weekends. For longer stays, bring sunscreen and a light jacket for mountain evenings. CTA: Download a SFO to DEN packing checklist and prepare for a comfortable September trip.
Nonstop flight time from San Francisco International Airport (SFO) to Denver International Airport (DEN) averages about 2 hours 20 minutes to 2 hours 40 minutes. In September you will typically find multiple daily nonstop departures in the early morning (6–9 AM), midday (11 AM–2 PM), and evening (5–9 PM). If you need flexible scheduling, look for multiple flights per day that allow same-day changes; for connections, plan at least 60–90 minutes minimum for domestic transfers at SFO or DEN. CTA: Check live SFO to DEN schedules for your specific September travel dates.
To find the cheapest flights from San Francisco International Airport (SFO) to Denver International Airport (DEN) in September, search flexible-date calendars, prioritize midweek travel (Tuesday–Thursday), and set fare alerts for price drops. Consider flying early in the morning or late at night, and compare nonstops vs one-stop itineraries—sometimes a short connection can save you significantly. Use multiple search engines, clear cookies or use incognito mode, and sign up for airline newsletters for flash sales. For immediate savings, check budget carriers like Southwest and seasonal promos from United and Alaska Airlines. CTA: Set up a price alert now and compare SFO to DEN fares for your September trip.