When to Start Marathon Training for an Autumn Race: A Summer Base-Building Timeline
Most 16-week marathon plans start in high summer without saying so out loud — they just assume you already have a base to build on. If you're eyeing an October or November marathon, the real question isn't "when does my plan start", it's "what am I supposed to be doing right now, in July, before it does".
Work backwards from race day
Most structured marathon plans run 12–18 weeks. Count back from your race date and that tells you when the formal plan begins — but the weeks before that aren't dead time. They're the base-building phase that determines how much the formal plan can actually load onto you.
| Race month | Formal plan starts | Base-building starts |
|---|---|---|
| September | Late May – June | Now, if you haven't already |
| October | June – July | July (this is you) |
| November | July – August | July–August |
What the base-building phase is actually for
- Building weekly mileage gradually so the formal plan's long runs don't arrive as a shock to your joints and tendons.
- Establishing an aerobic base at an easy, conversational effort — see our aerobic base-building plan for the specifics.
- Fixing niggles now, while there's no taper or race to protect, rather than three weeks before the start line.
- Practising your summer running logistics — hydration, timing, pacing by feel — since much of this base phase will run through the hottest weeks of the year.
A rough July–race-day timeline for an autumn marathon
- Weeks 1–4 (now): build weekly mileage by no more than ~10% a week, mostly easy running, one weekly long run growing gradually.
- Weeks 5–8: introduce one quality session a week (easy strides or a gentle tempo) alongside the growing long run.
- Formal plan begins: once you can comfortably run your target long-run distance for that point in a plan and handle 3–4 running days a week without lingering soreness.
- Final 3 weeks: taper — covered in our marathon recovery timeline for what happens after the race itself.
Why starting in summer heat is actually an advantage
Training through summer heat forces adaptations — increased plasma volume, earlier and heavier sweating — that carry over directly into cooler autumn racing conditions. Runners who build their base through the hardest heat of the year often find race day, weeks later in cooler weather, feels easier than their training did. It isn't a coincidence — see our guides on running in heat and humidity and adjusting a marathon plan for heat for how to train safely through this phase rather than avoiding it.
Signs you're starting too late
- Your longest run right now is under 8km and your race is under 14 weeks away.
- You're planning to jump straight into a plan's Week 1 long run without any recent running base.
- You have an old niggle you've been ignoring rather than addressing before mileage climbs.
None of these are disqualifying — they just mean shortening your goals (a run/walk finish, or a half marathon instead) is more realistic than forcing a compressed plan.
Frequently Asked Questions
Can I start marathon training in July for a November race?
Yes — that's an ideal window. You'll have roughly 4–6 weeks of base-building before a formal 12–16 week plan even needs to begin.
What if I haven't run consistently before this summer?
Spend longer in the base-building phase — 6–8 weeks rather than 4 — and consider whether a shorter autumn race (10K or half marathon) is the more realistic target this cycle.
Do I need to run through summer heat, or wait for autumn to start?
Train through it, adjusted for conditions — running by effort rather than pace, per our heat and humidity guide. Waiting for cooler weather leaves too little time to build the base a marathon needs.