The short answer is the first quarter of the year. The longer answer is that Jamaica's running seasons are separated by much less than a temperate runner expects, that the difference between a good month and a bad one is smaller than the difference between 06:00 and 08:00 on any single morning, and that the race calendar does not line up neatly with the conditions.
All the numbers below come from Verus's own climate archive: eleven years of hourly Open-Meteo records for Kingston, 2015-2025, sampled at the hours people actually set off rather than averaged across the day. A daily average includes the small hours nobody runs in and flatters tropical heat badly.
The whole year in one table
The index is air temperature plus dew point in Fahrenheit — the standard coaching rule of thumb. Its bands run 120-130 for a 1-2% penalty, 130-140 for 2-3%, 140-150 for 3-4.5% and 150-165 for 4.5-6% — a heuristic rather than a physiological model, which is why every one of them is a range. "Warm mornings" is the share of days starting at or above 24°C.
| Month | Index at 06:00 | Rain days | Warm mornings | Verdict |
|---|---|---|---|---|
| January | 139 | 5.8 | 2% | The best month of the year. Driest, coolest at dawn, and almost no warm mornings. |
| February | 139 | 8.4 | 1% | Equal best on the index, and the lowest share of warm mornings in the record. |
| March | 139 | 7.1 | 3% | Still at the yearly low. The last of the genuinely good window. |
| April | 143 | 9.0 | 9% | Turning. Four points worse at dawn and warm mornings starting to appear. |
| May | 148 | 10.7 | 43% | The step change. Nearly half of mornings now start above 24°C. |
| June | 150 | 7.0 | 67% | Peak index reached. Drier than May, but no easier. |
| July | 150 | 6.1 | 78% | Driest of the summer months, and joint hottest by daily high at 31.9°C. |
| August | 150 | 8.2 | 82% | The hardest month to run in. Four in five mornings start at or above 24°C. |
| September | 150 | 11.7 | 78% | Equal worst on the index and getting wet. The 10:00 index reaches 161. |
| October | 149 | 16.6 | 54% | The wettest month by a distance — rain on about two days in three. |
| November | 145 | 12.2 | 21% | Improving quickly, still wet. The turn back towards the good season. |
| December | 142 | 7.4 | 12% | Genuinely good again, and the month of the Reggae Marathon. |
What the table actually tells you
Three things stand out, and none of them is "it is hot in summer".
First, the index barely moves. Eleven points separate the best month from the worst. London's dawn index swings from 74 in January to 113 in July — thirty-nine points, a genuinely different sport at the two ends of the year. In Jamaica there is no off-season to hide in, and no month in which the heat stops being the main variable in your running.
Second, the warm-mornings column moves far more than the index does, and it is the number that best describes what changes. Going from 3% of mornings above 24°C in March to 82% in August is the difference you actually feel — not a few degrees of average, but whether a given morning is likely to be one of the manageable ones.
Third, the start time matters more than the month. Moving a September run from 06:00 to 10:00 costs eleven index points. Moving a run from August to January costs eleven index points. You can have the best month of the year by getting up two hours earlier — and if you get up late in January you have thrown the whole advantage away.
The one-line version
Choosing the right hour is worth as much as choosing the right month, and it is available to you 365 days a year rather than three.
The rain is a separate question
October is the wettest month on the record, with rain on about 16.6 days in an average month, followed by November at 12.2 and September at 11.7. That autumn peak matters more for safety and route choice than for comfort — see the safety guide on gullies and flowing water, which is the genuine hazard rather than a soaking.
It is also worth saying that rain during a run here is frequently a relief rather than an inconvenience. A shower drops the air temperature and gives your sweat somewhere to go for twenty minutes, which is why local runners are markedly less bothered by it than a visitor expects.
The Atlantic hurricane season runs 1 June to 30 November, overlapping the hardest running months. In an ordinary year that means a small number of days when running is simply off, rather than a season-long constraint.
When the races actually are
The Jamaican road calendar does not map onto the good conditions the way you would expect, largely because major events are anchored to charity dates, corporate sponsorship cycles and tourism seasons rather than to the dew point. The organisers deal with the heat by starting before dawn instead — pre-dawn guns are standard here, and one race on the calendar goes off at 06:00.
| Window | What is on | Conditions |
|---|---|---|
| December | Reggae Marathon, Half, 10K and 5K in Kingston; Runners Relief 15K | Good. Index 142, 7.4 rain days. |
| February-March | Sagicor SIGMA Corporate Run; Kingston City Run 10K and 5K | The best of the year. Index 139. |
| April-May | MoBay Night Run 5K; Jill Stewart MoBay City Run 10K; SHINE 5K Night Run | Deteriorating, which is why several of these are evening races. |
| September | Team Sangster 10K and 5K in Montego Bay; Caribbean Wellness Day 3K; The Blue Run 5K; Purple Run 3K | The hardest window on the calendar. Team Sangster starts at 06:00. |
| October-November | CIBC Walk For The Cure 5K; ICWI Pink Run 5K | Wet, improving. The charity-race cluster. |
If you are travelling specifically to race, December through March gives you both the best conditions and a real choice of events, with the Reggae Marathon weekend as the obvious anchor. If your dates are fixed in high summer, aim at the evening races and the 06:00 starts rather than fighting for a personal best.
If you are planning a trip around running
- 1 Aim for January to March if the dates are yours to choose. Best index, fewest warm mornings, driest weather and a good spread of races.
- 2 December is a close second and has the biggest race weekend of the year in it.
- 3 Avoid planning a goal race for August or September unless the event itself is the reason for the trip.
- 4 If you are coming in the wet autumn, build flexibility into long-run days rather than assuming a fixed weekly schedule.
- 5 Whatever month you land in, arrive two weeks before a goal race if you can. Acclimatisation is worth more than the difference between the best month and the worst.