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Delta Air Lines / SJC → SEA

DL 4100 on time

Delta Air Lines 4100: San Jose to Seattle at 8:59 p.m.; Seattle to San Jose at 5:50 p.m. (past 12 months). Figures below the title are for SJC → SEA, its busiest leg

On time
87%
199 flights · likely 82–91%
Cancelled
0.5%
of scheduled flights
Typical arrival
−17 min
median vs schedule
When late
+59 min
average delay
Similar flights
86%
DL, same route & hour

About 1 in 8 DL 4100 flights from San Jose arrived 15+ minutes late, diverted or cancelled over the past year (13%); 0.5% were cancelled. The typical flight landed 17 minutes early.

DL 4100: SJC → SEA

Scheduled to leave San Jose at 8:59 p.m. local time, operated by SkyWest as OO 4100. Over the past year it arrived on time 87% of the time (199 flights), in line with other DL flights on the route at that hour (86%). Last seen in the data Aug 31, 2026.

Usually Delta Air Lines's last flight of the day from San Jose to Seattle (100% of days). Delta Air Lines's last SJC–SEA flight was cancelled 0.3% of the time, against 0.2% for its earlier ones. If it's cancelled, the next Delta Air Lines flight is usually around 7:20 a.m. the next morning.

Month by month

40%70%100%Jan 2026: 83% on time (23 flights)83JanFeb 2026: 88% on time (24 flights)88FebMar 2026: 80% on time (30 flights)80MarApr 2026: 83% on time (30 flights)83AprMay 2026: too few flights (6 flights)MayJun 2026: 96% on time (24 flights)96JunJul 2026: 94% on time (31 flights)94JulAug 2026: 84% on time (31 flights)84Aug

By day of week

DayFlightsOn time
Monday3181%
Tuesday3090%
Wednesday3087%
Thursday2983%
Friday2986%
Saturday21100%
Sunday2986%

Why it was late

Airline (crew, maintenance, ops) 63%Severe weather 27%Air traffic & airport (NAS) 8%Security 2%

All flights SJC → SEA · Connecting off DL 4100? Check the risk

DL 4100: SEA → SJC

Scheduled to leave Seattle at 5:50 p.m. local time, operated by SkyWest as OO 4100. Over the past year it arrived on time 83% of the time (165 flights), in line with other DL flights on the route at that hour (82%). Last seen in the data Aug 31, 2026.

Month by month

40%70%100%Feb 2026: too few flights (13 flights)FebMar 2026: 73% on time (30 flights)73MarApr 2026: 93% on time (30 flights)93AprMay 2026: too few flights (6 flights)MayJun 2026: 96% on time (24 flights)96JunJul 2026: 87% on time (31 flights)87JulAug 2026: 68% on time (31 flights)68Aug

By day of week

DayFlightsOn time
Monday2580%
Tuesday2492%
Wednesday2488%
Thursday2479%
Friday2483%
Saturday2090%
Sunday2471%

Why it was late

Airline (crew, maintenance, ops) 84%Severe weather 8%Air traffic & airport (NAS) 6%Security 2%

All flights SEA → SJC · Connecting off DL 4100? Check the risk

Questions

How often is DL 4100 from SJC to SEA late?

Delta Air Lines 4100 from San Jose, CA to Seattle, WA arrived 15 or more minutes late, was diverted or was cancelled on 13% of 199 scheduled flights between September 2025 and August 2026. 0.5% were cancelled.

How often is DL 4100 from SEA to SJC late?

Delta Air Lines 4100 from Seattle, WA to San Jose, CA arrived 15 or more minutes late, was diverted or was cancelled on 17% of 165 scheduled flights between September 2025 and August 2026. 0.6% were cancelled.

Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Delta Air Lines for today's flight. Method.