Will Hong Kong have between 70-120mm of precipitation in October?

- [2026-10-15] HKO's "Climate Highlight" snippet gives October 2026 total rainfall of 77.4 mm up to 15 Oct, which is already above the 70 mm floor of the bracket. Year-to-date rainfall was 2529.3 mm. The page text carries a stale "last revision" stamp, and I could not load the live page to confirm the figure. https://www.weather.gov.hk/contente.htm - [2026-10-02] HKO's yesterday's-weather bulletin showed 0 mm on 1 Oct and 2451.9 mm year-to-date. 2529.3 − 2451.9 = 77.4 mm, so the 77.4 mm figure is consistent with the year-to-date change since 1 Oct. https://www.hko.gov.hk/textonly/v2/pastwx/ryestxt.htm - [2026-10-15] The Observatory forecast a fresh easterly airstream with "one or two showers" over the next 2–3 days. Saturday 17 Oct was mostly cloudy with one or two showers, and Sunday 18 Oct started mostly cloudy with one or two light showers. Rain on 16–18 Oct is not in the 77.4 mm figure and is likely small. https://www.thestandard.com.hk/news/article/345592/HK-unlikely-to-be-hit-as-Typhoon-Champi-gathers-strength - [2026-10-15] The Observatory forecast generally sunny, dry weather for early to mid the week of 19 Oct, with a northeast monsoon reaching southern China late that week. It predicted mostly sunny weather for the next nine days. https://www.thestandard.com.hk/news/article/345592/HK-unlikely-to-be-hit-as-Typhoon-Champi-gathers-strength - [2026-10-18] HKO 9-day forecast: 24 Oct mainly fine and dry, very hot, low probability of significant rain. 25 Oct sunny periods, dry, low probability. 26 Oct sunny intervals, low probability. https://www.weather.gov.hk/contente.htm - [2026-10-18] Timeanddate model forecast (a commercial model, not HKO): about 0.00" rain on 18–19 Oct. It gave small amounts later: roughly 0.07" on 22 Oct and 0.03" on 24 Oct. It showed a wetter 25 Oct at about 0.69" (~17 mm, 81% chance), but this page's cached snapshot looks older than today, so treat it as unreliable. https://www.timeanddate.com/weather/hong-kong/hong-kong/ext - [2026-10-15] Typhoon Champi, forming east of Guam, is expected to turn north near eastern Taiwan and head toward Japan. The Observatory said tropical cyclones are unlikely to affect Hong Kong for the rest of October. https://www.thestandard.com.hk/news/article/345592/HK-unlikely-to-be-hit-as-Typhoon-Champi-gathers-strength - [2026-10-07] The Observatory said the chance of a tropical cyclone directly affecting Hong Kong for the rest of October is low. It cited cooler South China Sea surface temperatures and an anticyclonic anomaly suppressing convection, which models show persisting through late October. https://www.thestandard.com.hk/news/article/344865/Typhoon-season-winds-down-as-HK-faces-low-October-risk - [2026-10-08] Dimsumdaily reported the same HKO assessment: only three tropical cyclones have come within 500 km of Hong Kong this year. https://www.dimsumdaily.hk/hong-kong-observatory-says-low-chance-of-direct-tropical-cyclone-impact-for-rest-of-october/ - [2026-10 (HKO monthly outlook)] HKO's monthly forecast for October 2026 was normal to below-normal rainfall. The anticyclone was expected to weaken slightly in the latter part of the month, favouring somewhat more rain. The page also notes a strong El Niño developing. https://www.hko.gov.hk/en/wxinfo/month/month.htm - [2026-10-18] Third-party daily model totals (weather25, easeweather) suggest light rain at most on a few days in the remaining month, such as 21 and 28 Oct. They are low-reliability. https://www.weather25.com/asia/hong-kong?page=month&month=October BOTTOM LINE: About 77.4 mm had fallen by 15 Oct, which is already inside 70–120 mm, and the 16–18 Oct showers add little. For the bracket to fail, the month would need to climb about 43 mm or more from here to pass 120 mm. The outlook is dry with low tropical-cyclone risk, though a late-month northeast monsoon surge or a rain event could still add rain. NOT FOUND: HKO's Daily Extract table for October 2026 (both fetches returned empty or timed out), official rainfall for 16–18 Oct, and any HKO forecast of rainfall amounts for 27–31 Oct.

- [2026-10-15] HKO's Climate Highlight showed October 2026 rainfall at **77.4 mm up to 15 Oct**, so the 70 mm floor was already passed. HKO's page was last revised 18 Sep 2026, but it shows forecasts dated 20–26 Oct, so it was served recently. Only 4–5 mm of daily rainfall at most normally falls in a given day this time of year. https://www.weather.gov.hk/contente.htm - [2026-10-17] HKO's 9-day forecast (issued 17 Oct) has sunny or sunny-interval weather through 26 Oct, with "Low" probability of significant rain on each day. https://www.hko.gov.hk/textonly/v2/forecast/nday_v2.htm - [2026-10-18] Forecast for 20–26 Oct: fine and dry with low significant-rain probability each day. One or two rain patches are possible on 21–22 Oct. https://www.weather.gov.hk/contente.htm - [2026-09-30] HKO's monthly forecast for October 2026 said rainfall would probably be normal to below-normal. It expected a weak northeast monsoon and an anticyclone aloft, which would weaken a little late in the month and favour somewhat more rain. El Niño is established and forecast to become very strong. https://www.hko.gov.hk/en/wxinfo/month/month.htm - [2021] The 1991–2020 October normal is **120.3 mm**, with 7.83 rain days and 0.77 days of 50 mm or more. https://www.hko.gov.hk/en/cis/normal/1991_2020/normals.htm - [2021] The 1991–2020 half-month normals are 76.6 mm for 1–15 Oct and 43.7 mm for 16–31 Oct. https://www.weather.gov.hk/en/cis/normal/1991_2020/15day_normal.htm - [2021-11-02] October 2021 totalled 631.1 mm, the second highest October on record. One day (8 Oct) gave 329.7 mm. https://www.weather.gov.hk/en/wxinfo/pastwx/mws2021/mws202110.htm - [2022-11] October 2022 totalled 49.9 mm. https://www.hko.gov.hk/en/wxinfo/pastwx/mws2022/mws202210.htm - [2024-11] October 2024 totalled 11.3 mm. https://www.hko.gov.hk/en/wxinfo/pastwx/mws2024/mws202410.htm - [2025-11-04] October 2025 totalled 31.2 mm, about 26% of normal. https://www.hko.gov.hk/en/wxinfo/pastwx/mws2025/mws202510.htm - [2026-10-08] The Standard reported that HKO sees a low chance of a direct typhoon hit for the rest of October. Three systems (Choi-wan, Koguma, Nolo) were expected to track north toward Japan. https://www.thestandard.com.hk/news/article/344936/Hong-Kong-unlikely-to-face-direct-typhoon-hit-for-rest-of-October-HKO-says - [2026-10-05] SCMP reported an amber rainstorm warning on 5 Oct and a possible typhoon signal from Narra around 6–7 Oct. This is consistent with most of the 77.4 mm falling early in the month. https://www.scmp.com/topics/hong-kong-weather BOTTOM LINE: Climatologically, October is a skewed month. The 1991–2020 mean is 120.3 mm, and recent Octobers (2022, 2024, 2025) were well under 70 mm, while 2021 was far above 120 mm. For 2026, 77.4 mm was already recorded by 15 Oct, so the outcome now hinges on staying under 120 mm. The 20–26 Oct forecast is dry, and the normal for 16–31 Oct is only about 44 mm, so a total of roughly 77–120 mm is the central expectation. A YES would be lost only if about 43 mm or more falls in the last two weeks. NOT FOUND: Daily rainfall for 16–18 Oct 2026, which means the exact total to date is unconfirmed (the daily extract page timed out). Also not found: a full multi-decade distribution of October totals and any prediction-market data.

YES means: HKO's total October 2026 rainfall (Daily Extract, 1–31 Oct) comes in between 70.0 and 120.0 mm. A value that falls exactly between brackets resolves to the higher bracket. - [2026-10-18] HKO's yesterday's-weather bulletin (issued 00:15 on 18 Oct) gives 17 Oct rainfall as "Trace". Year-to-date was still 2529.3 mm, the same figure as the 15 Oct Climate Highlight. So 16 and 17 Oct added essentially nothing, and the total through 17 Oct is still about 77.4 mm. That is above the 70 mm floor. The earlier "16–18 Oct showers add little" assumption is now confirmed for 16–17 Oct. https://www.hko.gov.hk/textonly/v2/pastwx/ryestxt.htm - [2026-10-18] HKO's 9-day forecast (updated 11:30 on 18 Oct) has 19–24 Oct as fine or mainly fine, with a "Low" probability of significant rain (PSR) each day. Only scattered patches are mentioned: light patches on the night of 21 Oct, patches on 22 Oct, and showers on the night of 24 Oct. 25 Oct is "mainly cloudy with a few showers" with PSR "Medium Low". 26 and 27 Oct are "one or two showers" with PSR "Low". This differs slightly from the earlier report that 25 Oct was dry. The wording describes light showers, not rainstorms. https://www.hko.gov.hk/textonly/v2/forecast/nday_v2.htm - [2026-10-18] The same HKO bulletin says Champi's "outer subsiding air" will bring mainly fine, high-temperature weather to southern China in the latter part of the week. This holds even if the storm heads toward the southeast China coast. The suppression by an anticyclone aloft applies through about 24 Oct. https://www.hko.gov.hk/textonly/v2/forecast/nday_v2.htm - [2026-10-18] Dimsumdaily, relaying HKO's weekend essay, says an anomalous anticyclonic flow over the South China Sea since late September has suppressed deep convection, and the northeast monsoon has been weak. It adds that the European and US models bring Champi west toward the southeast China coast, while an AI model recurves it north to the Ryukyus. HKO says the northeast monsoon would wear a westbound storm down. This is the main tail risk for exceeding 120 mm, and it is the opposite of the earlier "unlikely to affect HK" framing. https://www.dimsumdaily.hk/hk-observatory-expects-super-typhoon-champi-to-keep-strengthening/ - [2026-10-18] PAGASA says Champi is a super typhoon about 2,090 km east of southeastern Luzon. It is expected to enter the Philippine area on 20 Oct, is more likely to head for Taiwan than the Philippines, and landfall in the Philippines looks unlikely. Any path toward Hong Kong would need to cross Luzon Strait waters after about 23 Oct, which leaves roughly a week for rain to build up. https://www.rappler.com/philippines/weather/super-typhoon-champi-itcz-easterlies-update-pagasa-forecast-october-18-2026-11am/ - [2026-10-02] A northeast monsoon surge brought localized heavy rain and thunderstorms on 2 Oct, with showers continuing into 3 Oct. This fits most of the 77.4 mm having fallen early in the month. It shows that a weak-monsoon month can still deliver one burst of 70 mm or more, and it supports a YES floor that does not depend on the remaining 13 days. https://english.dotdotnews.com/a/202610/02/AP6abf10a4e4b02724bdb62ff4.html - [2026-09-30] HKO's seasonal outlook for Oct–Dec 2026 is normal to above-normal rainfall, as of 30 Sept. This contrasts with the October monthly outlook of normal to below-normal. It gives a way for rain to arrive late in the year. But October is already near its likely total, so it adds little for 70–120 mm. https://www.hko.gov.hk/en/wxinfo/season/season.htm - [2026-10-18] AccuWeather's 10-day model shows "occasional afternoon rain" on 26 Oct and a "little p.m. rain" on 27 and 28 Oct, with cooler highs of 80–85°F. This points to a modest late-month shift toward showers, consistent with HKO's "somewhat more rain" in the latter part of the month. Amounts are not given, and it is a commercial model. https://www.accuweather.com/en/hk/hong-kong/1123655/october-weather/1123655 - [2026-10-18] The climatological 16–31 Oct normal is 43.7 mm (colleague's figure). The sum of the 77.4 mm already recorded and a normal rest of month is about 121 mm. HKO's dry 19–24 Oct outlook points below that normal for those days. The 16–17 Oct trace puts the rest-of-month total starting at 0. About 42.6 mm must fall in 18–31 Oct to reach 120 mm. A normal fortnight's rainfall would be just on the line, but this year's pattern is drier than normal. BOTTOM LINE: The strongest YES case is that the 70 mm floor is already cleared (about 77.4 mm through 17 Oct) and the next 6–9 days are forecast dry. A YES then needs 18–31 Oct to bring less than about 42.6 mm, which is likely under a suppressed-convection pattern. The single path to YES is a dry or showery finish, with scattered light rain around 21–27 Oct and Champi recurving or staying away. NOT FOUND: HKO's finalized Daily Extract for October 2026; the official rainfall for 18 Oct; HKO's rainfall amounts for 27–31 Oct; and any tracked model ensemble probabilities for Champi reaching Hong Kong.

YES means: HKO's October 2026 "Total Rainfall (mm)" for Hong Kong comes out between 70.0 and 120.0 mm. A figure falling exactly between brackets goes to the higher bracket. - [2026-10-18] HKO's yesterday's-weather bulletin (00:15 HKT 18 Oct) shows rainfall on 17 Oct was only "Trace". Year-to-date is still 2529.3 mm, identical to the 15 Oct figure. So the 77.4 mm month-to-date (via the 1 Oct baseline of 2451.9) held through 17 Oct, with no addition on 15–17 Oct. For NO, October needs at least 42.7 mm more after 17 Oct, i.e. a month above 120.0 mm. https://www.hko.gov.hk/textonly/v2/pastwx/ryestxt.htm - [2026-10-18] HKO's 11:30 HKT 9-day forecast has no significant rain for 19–24 Oct, with PSR "Low" daily. The only wet signals are one or two light rain patches on 21–22 Oct and showers at night on 24 Oct. 25 Oct is the wettest day, "a few showers" with PSR "Medium Low". 26–27 Oct are "one or two showers", PSR "Low". Nothing in it points to a 40 mm-plus event. https://www.hko.gov.hk/textonly/v2/forecast/nday_v2.htm - [2026-10-18] The same bulletin names the main NO route: Champi is still uncertain and has "a chance" of moving toward the southeastern China coast. HKO's central expectation is a turn north toward the Ryukyus, with outer subsiding air giving fine, hot weather late this week. A midweek northeast monsoon surge is also expected. These are tail risks, not the base case. https://www.hko.gov.hk/textonly/v2/forecast/nday_v2.htm - [2026-10-18] The remainder of October 2026 would need about 43 mm, roughly the whole 1991–2020 16–31 Oct normal of 43.7 mm (colleague report), in a forecast-dry, anticyclone-dominated fortnight. The remaining 13 days (18–31 Oct) are mostly covered by the 9-day forecast through 27 Oct, which shows at most light showers. Only 28–31 Oct is beyond the forecast window. Alternatively, HKO would need to show a day totalling 40 mm or more. - [2026-10-02] A northeast monsoon with thunderstorms brought heavy localised rain on 2 Oct, with continuous cloudy, rainy weather forecast for the following days. That fits most of the 77.4 mm having fallen in the first week (consistent with the 5 Oct amber rainstorm in colleague reports). The rain-prone early-month pattern has since given way to dry conditions. https://english.dotdotnews.com/a/202610/02/AP6abf10a4e4b02724bdb62ff4.html - [2026-10-18] The cumulative rainfall figure only rises, so the bracket's 70 mm floor is already secured. On the resolution mechanics, the August-style "revision" clause cuts against late changes: the market ignores revisions after the data is finalised. The Daily Extract is the stated source, and the bulletin's own note calls the readings provisional with limited validation. Any small difference between the provisional and final HKO figure would matter only if the total were very near 120.0 mm. - [2025-11] Recent Octobers show how dry late-month spells run. In 2025, October rain after the early-month Matmo event was mostly "a few rain patches" under a northeast monsoon and cloud band from 20 Oct on, and the month totalled only 31.2 mm. A monsoon surge in late October typically brings light drizzle, not big totals. https://www.hko.gov.hk/en/wxinfo/pastwx/mws2025/mws202510.htm - [2024-11-04] October 2024 is a precedent for suppressed autumn rain under a weak northeast monsoon: the month was warmest on record and totalled 11.3 mm, about 9% of normal. HKO's 2026 monthly outlook uses similar language (weak monsoon, anticyclone aloft, normal to below-normal rain). https://www.hko.gov.hk/en/wxinfo/pastwx/mws2024/mws202410.htm - [2026-10-18] Hedge from the other side: HKO's seasonal outlook for Oct–Dec 2026 is for normal to above-normal rainfall, and the strong El Niño is a wet-lean signal for later months. That outlook is for the quarter, not the last two weeks of October. https://www.hko.gov.hk/en/wxinfo/season/season.htm - [2026-10-18] AccuWeather's commercial forecast shows occasional showers around 26–28 and 31 Oct, with no heavy-rain wording. It is low-reliability and does not contradict HKO. https://www.accuweather.com/en/hk/hong-kong/1123655/october-weather/1123655 BOTTOM LINE: The status quo, 77.4 mm with a dry forecast through 24 Oct and only light showers through 27 Oct, already sits inside 70–120 mm. NO needs a roughly 43 mm event in the final days, which is most plausible only from a Champi track surprise or a wet late-month monsoon or trough. NOT FOUND: The HKO Daily Extract table for October 2026, and the official finalised monthly total. Also not found: HKO rainfall-amount forecasts for 28–31 Oct, and an updated Champi track toward the China coast beyond HKO's "chance" wording.