The December marathon might feel a long way off, but spoiler alert, it isn't. The BYD Singapore International Marathon presented by adidas runs 4–6 December 2026, and if you're targeting the full 42.195km, you're now about 12 to 13 weeks out. Eeep! We hear you… Everything you do to earn a strong race day starts around now — and it all has to happen in 30°C heat and soup-like humidity, which changes how a marathon block should actually be run.
Most training plans you'll find online were written for cool mornings in Europe or the US. Here's a simpler way to think about the next 12 weeks, built for Singapore conditions.
Work backwards from race day first
Before you run a single step, count the weeks. Race weekend is 4–6 December. Work back and you get roughly four phases: a few weeks of base, a longer block of specific marathon work, then a taper into race week. If you're reading this in early September, you have enough runway to do it properly without cramming. If you're picking this up later in the month, you'll trim the base phase, not the taper.
A realistic heat-adapted structure looks like this:
|
Phase |
Weeks out |
Focus |
|---|---|---|
|
Base |
12–10 |
Easy mileage, get the long run rolling, build heat tolerance |
|
Build |
9–5 |
Longest runs, marathon-pace work, tempo efforts |
|
Sharpen |
4–3 |
Peak long run, then start pulling volume back |
|
Taper |
2–0 |
Cut volume, keep some intensity, arrive fresh |
Want a printable PDF version of your 12 week training plan? Download it here.
Photo by Delon Ho
What a typical week looks like
You don't need to run every day to run a good marathon. For most working adults training around a job and family, four to five runs a week is plenty. A workable rhythm through the build: one long run, one faster session (tempo or marathon-pace work), and two or three easy runs to fill in the mileage. Keep one full rest day, and treat it as sacred.
Pro tip: Avoid making your easy runs too hard and your hard runs too soft, so everything blurs into one medium effort. Easy days should be genuinely easy so that your quality sessions have something in the tank. In the heat, that discipline matters even more, because the margin for pushing through fatigue is thinner than it would be in cooler weather.
Photo by Delon Ho
Run by effort, not by pace
This is the single biggest adjustment for training in Singapore. Heat and humidity raise your heart rate and slow you down at any given effort. If your plan says 5:30/km for an easy run and you're gasping to hold it at 6am in 85% humidity, you need to make some tweaks to your plan.
Anchor your easy and long runs to effort or heart rate instead. Easy should feel genuinely easy, i.e you can hold a conversation. Save the pace-watching for your marathon-pace segments, and even then, expect your sustainable heat pace to sit slower than your cool-weather goal. That gap is normal. We covered why the heat does this in Heat Happens, and it's worth a read before you get frustrated with your splits.
Pro tip: A GPS watch earns its place here, because effort-based training is much easier when you can actually see heart rate, cadence and drift over a run. A COROS watch handles the whole build — the PACE line covers everything a marathoner needs, with battery that laughs off a three-hour long run. Having honest data stops you from guessing whether you went too hard.
Protect the long run — and time it right
The long run is the backbone of any marathon block. In Singapore, when you do it matters as much as how far. Start before dawn. By 8am the sun is already punishing, and a 2.5-hour long run that begins at 5:30am is a completely different experience from one that begins at 7am.
Pro-tip: Build the distance gradually and don't panic if a hot morning turns your long run into a slog — that's the training effect doing its job. Two things make these runs survivable: carrying your own fluid, and taking electrolytes seriously. You lose a lot of salt sweating here, and plain water alone can leave you flat or cramping late in a run. Keep it simple with something like SaltStick FastChews or BIX Active Electrolytes and practise using them on every long run, not just on race day.
Photo by Delon Ho
Pick shoes now, not in race week
Whatever you race in December, you should be running in it well before then. Race week is the worst possible time to break in new shoes. Most runners want two pairs for a marathon build: a cushioned daily trainer that soaks up easy miles, and something lighter for faster work and eventually the race.
For daily mileage, a well-cushioned trainer like the Topo Athletic Cyclone 3 takes the sting out of high-volume weeks. If you're weighing up a carbon-plated race shoe versus a daily trainer for the big day, we'll cover that in detail in a future post — for now, just get the miles in on shoes you trust.
Pro tip: Not sure what fits your foot and stride? That's exactly what an in-store fitting is for. Head over to 108 Sims Ave, where our experienced RDRC staff will be excited to help you find the right shoe for your needs.
Photo by Delon Ho
Recover like it's part of training, because it is
Heat training carries a hidden cost: you're more fatigued than the numbers suggest, because your body is also working hard just to cool itself. Sleep is your best recovery tool, full stop. After that, hydrate through the day (not just around runs), respect your rest days, and watch for the early signs you're digging a hole — broken sleep, a resting heart rate that won't settle, sessions that feel harder than they should. If that's you, back off before it becomes an injury.
Our guide to the warning signs of overtraining is worth bookmarking for the deeper weeks of the build.
The one-line version
Start now, run by effort, protect your long run, sort your shoes and electrolytes early, and sleep like it's your job. Do that for 12 weeks and you'll line up in December ready to run the day you trained for — heat and all.
Kitting out for the December build? Come talk to us — we'll help you match shoes, a watch and a fuelling plan to how you actually train.
New to the longer stuff? Our 6 Weeks to UTSG guide shows the same work-back thinking applied to a trail race.