Cool Air, South Africa

1. Sun8 AM65°9 mph
2. 9 AM67°8 mph
3. 10 AM67°9 mph
4. 11 AM66°10 mph
5. 12 PM66°11 mph
6. 1 PM65°11 mph
7. 2 PM63°12 mph
8. 3 PM61°12 mph
9. 4 PM60°12 mph
10. 5 PM59°11 mph
11. 6 PM58°12 mph
12. 7 PM57°10 mph
13. 8 PM57°10 mph
14. 9 PM56°10 mph
15. 10 PM56°10 mph
16. 11 PM55°9 mph
17. Mon12 AM55°9 mph
18. 1 AM54°9 mph
19. 2 AM54°8 mph
20. 3 AM53°8 mph
21. 4 AM53°9 mph
22. 5 AM53°9 mph
23. 6 AM53°9 mph
24. 7 AM54°8 mph
25. 8 AM55°8 mph
26. 9 AM56°8 mph
27. 10 AM56°7 mph
28. 11 AM57°7 mph
29. 12 PM58°6 mph
30. 1 PM59°7 mph
31. 2 PM59°7 mph
32. 3 PM59°7 mph
33. 4 PM58°8 mph
34. 5 PM56°10 mph
35. 6 PM54°9 mph
36. 7 PM53°7 mph
37. 8 PM53°7 mph
38. 9 PM53°6 mph
39. 10 PM53°6 mph
40. 11 PM52°5 mph
41. Tue12 AM51°4 mph
42. 1 AM50°4 mph
43. 2 AM50°6 mph
44. 3 AM51°7 mph
45. 4 AM51°7 mph
46. 5 AM49°6 mph
47. 6 AM49°5 mph
48. 7 AM52°8 mph

Scroll sideways for more hours. Pick an hour for every number.

1. TodaySep 2767°53°Heavy rain—0.17 inwind 12 mph
2. MonSep 2859°49°Cloudy—wind 10 mph
3. TueSep 2960°52°Partly cloudy—wind 9 mph
4. WedSep 3063°50°Rain showers—0.05 inwind 6 mph
5. ThuOct 171°52°Clear—wind 11 mph
6. FriOct 279°55°Clear—wind 11 mph
7. SatOct 380°60°Mostly clear—0.01 inwind 8 mph
8. SunOct 475°58°Cloudy—0.05 inwind 13 mph
9. MonOct 568°60°Rain—0.22 inwind 13 mph
10. TueOct 671°60°Light rain—0.35 inwind 11 mph
11. WedOct 7~62°56°Model mean0.10 in
12. ThuOct 8~83°55°Model mean
13. FriOct 9~80°59°Model mean0.07 in
14. SatOct 10~78°60°Model mean0.03 in
15. SunOct 11~82°59°Model mean
16. MonOct 12~90°61°Model mean0.14 in

• Feels like65°
• WindSSE 9 mph
• Humidity82%
• Dew point60°
• Pressure29.98 inHg
• UV index2 · Lowclear-sky peak 9 today
• Sunrise and sunsetSunrise · Sunset
• Moonrise6:54 PMMoonset 5:48 AM
• Moon phaseFull moon99% lit

Each line is one model’s own forecast at its own grid cell: three kilometers for HRRR, a quarter of a degree for the global models, which can sit a few hundred meters above or below the town. Where they agree the forecast is settled; where they part is where it is not.

NWS gridGFSGEFS ± spreadECMWFECMWF AI

A ~ marks a high or low read from six-hourly steps, which miss the true extreme by a degree or two.

ECMWF ensemble meteogram

10 daysTemperature plume

None of these is a measurement. Each is a rating of the forecast ahead, and of what is happening at the point right now, against what the activity or the ailment is known to mind, and each names the figure that decided it. An ailment or a pest is rated as a risk, low to extreme; an activity, a chore or a journey as a condition, poor to ideal.

Each rating says which span it is for: the rest of today’s daylight, tonight, or the next 24 hours.

Tonight has no dark, clear hour without a bright moon in this forecast. Rated poor.

Dark is the sun 18 degrees below the horizon; where it never gets that low, 12 degrees, marked nautical. Clear is sky cover of 20% or less. A bright moon is one above the horizon with a quarter or more of its disc lit. Transparency in the table is estimated from surface humidity (70% and 85% mark fair and poor) and visibility, since the forecast carries no haze or high cloud moisture. Seeing and transparency by hour, where shown, are Environment and Climate Change Canada’s astronomy forecast (regional model; seeing from cloud, wind shear, turbulence near the ground and the surface temperature trend; transparency from the moisture through the whole air column), under the Open Government Licence - Canada. Dew is the air within 2 °C of its dew point. Excellent is four or more clear moonless hours with good transparency; good is three; fair is one, or two clear hours.

Golden hour is the sun between 6 degrees above the horizon and 4 degrees below it; blue hour is the sun between 4 and 6 degrees below. These are the definitions timeanddate.com and PhotoPills use. Directions are degrees clockwise from true north, where the sun’s upper edge and the moon’s center cross a flat horizon; hills and buildings change both. None means the sun does not reach that height on the day; all day means it stays inside the band.

Hours fit for spraying, and the days dry enough for fieldwork and hay, read from this forecast’s wind, gusts, humidity, temperature and rain.

Spraying windows

• Mon 5 AM to 7 PM 14 hours, every hour within the rules
• Tue 7 AM to 4 PM 9 hours, every hour within the rules
• Wed 2 PM to 8 PM 6 hours, every hour within the rules
• Thu 8 AM to 8 PM 12 hours, some with delta T between 8 and 10 °C
• Fri 2 AM to 2 PM 12 hours, every hour within the rules
• Fri 8 PM to Sat 8 AM 12 hours, every hour within the rules

Good Marginal No

Field days

Spraying: sustained wind 3 to 10 mph, the range US extension services and most labels give; gusts no more than 15 mph (this page’s limit); delta T (air minus wet-bulb temperature) 2 to 8 °C preferred and 8 to 10 °C marginal, from GRDC guidance, with the wet bulb by Stull’s formula; no hour at a 30% chance of rain or 0.25 mm forecast during the rain-free time. Follow the product label, which overrides all of this. Field days: dry is no daytime hour at a 30% chance and under 1 mm all day, wet is 6 mm (0.25 in) or more; soil moisture is not in the forecast, so ground still wet from earlier rain is not accounted for. Hay drying marks a dry day with humidity down to 50% and a breeze of 5 mph or more.

The best-rated day this week is Sunday, rated best.

Periods in bold fall within an hour of sunrise or sunset. The weather’s side is the fishing index · Solunar tables for Cool Air, by month

Major periods are two hours centered on the moon’s passage overhead and underfoot; minor periods are one hour centered on moonrise and moonset: the conventional durations of John Alden Knight’s solunar tables (1936). The rating is this site’s: one point to start, two more within a day and a half of a new or full moon (one more within three and a half days), and one more when a period falls within an hour of sunrise or sunset. The theory has mixed support in fisheries research; the times are exact astronomy.

1. Today67° · SSE 7–12 mph

   Heavy rain. High near 19°C. Southsoutheast wind 12 to 20 km/h. Precipitation around 4 mm.

2. Tonight53° · S 7–12 mph

   Light rain. Low near 12°C. South wind 12 to 19 km/h.

3. Monday59° · SSE 6–9 mph

   Cloudy. High near 15°C. Southsoutheast wind 10 to 15 km/h.

4. Monday Night49° · S 4–9 mph

   Partly cloudy. Low near 10°C. South wind 7 to 14 km/h.

5. Tuesday60° · SSE 5–9 mph

   Partly cloudy. High near 16°C. Southsoutheast wind 8 to 14 km/h.

6. Tuesday Night52° · SE 2–7 mph

   Cloudy. Low near 11°C. Southeast wind 4 to 12 km/h.

7. Wednesday63° · ESE 2–6 mph

   Rain showers. High near 17°C. Eastsoutheast wind 4 to 10 km/h. Precipitation around 1.1 mm.

8. Wednesday Night50° · NNE 6–6 mph

   Partly cloudy. Low near 10°C. Northnortheast wind 9 to 10 km/h.

9. Thursday71° · N 8–9 mph

   Clear. High near 22°C. North wind 13 to 14 km/h.

10. Thursday Night52° · NNE 6–11 mph

    Clear. Low near 11°C. Northnortheast wind 10 to 18 km/h.

11. Friday79° · N 6–10 mph

    Clear. High near 26°C. North wind 10 to 16 km/h.

12. Friday Night55° · NNE 5–8 mph

    Clear. Low near 13°C. Northnortheast wind 8 to 13 km/h.

13. Saturday80° · NE 2–7 mph

    Mostly clear. High near 27°C. Northeast wind 4 to 12 km/h.

14. Saturday Night60° · S 2–4 mph

    Rain. Low near 15°C. South wind 3 to 6 km/h. Precipitation around 1.1 mm.

15. Sunday75° · ENE 2–10 mph

    Cloudy. High near 24°C. Eastnortheast wind 3 to 16 km/h.

16. Sunday Night58° · NE 10–13 mph

    Cloudy. Low near 15°C. Northeast wind 16 to 21 km/h.

17. Monday68° · NNE 7–11 mph

    Rain. High near 20°C. Northnortheast wind 12 to 17 km/h. Precipitation around 3 mm.

18. Monday Night60° · NNE 7–8 mph

    Heavy rain. Low near 16°C. Northnortheast wind 12 to 13 km/h. Precipitation around 11 mm.

19. Tuesday71° · NE 7–11 mph

    Light rain. High near 21°C. Northeast wind 12 to 18 km/h. Precipitation around 0.6 mm.

Climate of Cool Air: normals, records and every month

The forecast office edits about sixty fields for every cell of its grid. The common ones are above; these are the rest, as the daily extreme, for anyone who needs the mixing height, the fire danger or the swell.