Hawkesbury
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hawkesbury clear sky chart from 2005-11-05 to 2017-11-30.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
29%
14929
13%
47777
8%
14898
36%
14898
16%
34405

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
14%
720
7%
2506
3%
716
18%
716
7%
2046
January16th to endNight
19%
768
10%
2685
5%
768
26%
768
10%
2027
February1st to 15thNight
18%
703
10%
2287
4%
701
26%
701
11%
1781
February16th to endNight
20%
631
13%
1916
5%
631
28%
631
12%
1453
March1st to 15thNight
19%
720
13%
2144
7%
720
27%
720
13%
1636
March16th to endNight
29%
768
19%
2004
8%
768
36%
768
22%
1401
April1st to 15thNight
25%
718
15%
1796
4%
718
30%
718
20%
1331
April16th to endNight
25%
648
16%
1728
5%
648
33%
648
20%
1225
May1st to 15thNight
28%
360
16%
1440
11%
360
40%
360
15%
967
May16th to endNight
33%
375
13%
1497
10%
374
45%
374
17%
974
June1st to 15thNight
31%
360
8%
1440
6%
360
39%
360
12%
1011
June16th to endNight
42%
360
9%
1440
12%
360
46%
360
17%
931
July1st to 15thNight
51%
340
13%
1360
19%
340
57%
340
23%
782
July16th to endNight
52%
376
12%
1418
16%
354
55%
354
23%
839
August1st to 15thNight
54%
388
14%
1459
13%
386
60%
386
21%
933
August16th to endNight
51%
741
19%
1887
9%
741
55%
741
35%
1210
September1st to 15thNight
46%
720
14%
1800
7%
720
48%
720
28%
1255
September16th to endNight
48%
717
22%
1949
14%
717
53%
717
31%
1253
October1st to 15thNight
33%
720
17%
2154
10%
720
43%
720
20%
1471
October16th to endNight
25%
768
12%
2439
7%
768
32%
768
14%
1828
November1st to 15thNight
26%
760
17%
2492
10%
760
36%
760
15%
1778
November16th to endNight
20%
780
11%
2728
6%
780
27%
780
9%
2091
December1st to 15thNight
17%
720
8%
2520
3%
720
23%
720
8%
2018
December16th to endNight
11%
768
10%
2688
3%
768
19%
768
7%
2164

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
19%9%36%5%34446%31%
48645
Night
19%10%36%5%34445%32%
47946
Cloud CoverDay
19%8%36%5%34446%32%
48654
Night
18%9%46%5%34445%32%
47952
TransparencyDay
52%6%11%18%9%1
48332
Night
52%6%11%19%9%1
47777
SeeingDay
23%14%27%21%10%2
5770
Night
23%12%28%24%9%
14930

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
23%16%5%8%7%2433419%
1432
16th to endDay
15%15%6%8%5%26%5%45%24%
1536
February1st to 15thDay
14%14%5%11%7%35%346%23%
1575
16th to endDay
17%14%48%7%34445%25%
1557
March1st to 15thDay
18%12%410%6%3434427%
1805
16th to endDay
18%8%34434345%38%
2220
April1st to 15thDay
23%10%35%423335%33%
2152
16th to endDay
21%8%26%424345%35%
2244
May1st to 15thDay
22%7%36%5%25%345%31%
2511
16th to endDay
21%6%35%5%35%447%33%
2618
June1st to 15thDay
23%7%35%5%35%447%29%
2520
16th to endDay
20%5%35%5%35%5%7%8%28%
2520
July1st to 15thDay
15%5%25%6%35%5%6%9%35%
2520
16th to endDay
13%6%35%6%45%6%7%8%32%
2654
August1st to 15thDay
13%6%37%6%36%6%5%6%34%
2490
16th to endDay
11%5%24435%5%5%8%42%
2303
September1st to 15thDay
18%6%2342445%7%40%
2160
16th to endDay
17%424313346%47%
2010
October1st to 15thDay
23%8%25%5%2334435%
1806
16th to endDay
26%10%37%7%3434424%
1785
November1st to 15thDay
18%8%46%5%345%47%30%
1693
16th to endDay
26%11%36%5%23335%26%
1558
December1st to 15thDay
26%14%5%8%5%34335%18%
1440
16th to endDay
24%17%7%7%5%1334319%
1536
January1st to 15thNight
20%17%6%9%5%3434419%
2506
16th to endNight
13%15%5%8%7%35%445%25%
2685
February1st to 15thNight
13%13%7%10%8%3435%5%23%
2285
16th to endNight
17%11%5%9%6%34445%27%
1916
March1st to 15thNight
20%11%47%6%24435%28%
2131
16th to endNight
16%9%35%43334440%
2004
April1st to 15thNight
25%7%345%24245%34%
1796
16th to endNight
21%8%25%43343438%
1728
May1st to 15thNight
22%7%36%5%24445%34%
1440
16th to endNight
19%7%3442345%6%37%
1495
June1st to 15thNight
22%8%45%5%245%46%30%
1440
16th to endNight
16%6%25%425%6%5%7%36%
1440
July1st to 15thNight
10%5%244335%6%9%43%
1440
16th to endNight
11%4245%25%46%8%42%
1514
August1st to 15thNight
11%6%24435%6%7%9%38%
1469
16th to endNight
11%41443435%7%48%
1887
September1st to 15thNight
17%5%25%433447%41%
1800
16th to endNight
17%5%13323445%48%
1949
October1st to 15thNight
20%7%25%42435%6%38%
2154
16th to endNight
25%8%36%5%33345%29%
2439
November1st to 15thNight
22%8%36%5%33345%33%
2492
16th to endNight
22%12%48%6%25%435%25%
2728
December1st to 15thNight
22%15%5%7%6%3444421%
2520
16th to endNight
24%17%47%5%3433321%
2688

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
23%14%49%7%26%33419%
1432
16th to endDay
14%17%5%7%5%35%5%45%24%
1536
February1st to 15thDay
14%13%6%10%7%3435%5%23%
1575
16th to endDay
18%13%5%7%6%44345%25%
1557
March1st to 15thDay
18%11%5%9%7%35%33427%
1815
16th to endDay
18%7%45%5%24445%38%
2219
April1st to 15thDay
24%9%45%5%22335%33%
2152
16th to endDay
20%8%36%424345%35%
2244
May1st to 15thDay
21%8%36%5%345%45%33%
2511
16th to endDay
21%5%35%5%25%447%33%
2618
June1st to 15thDay
22%7%35%5%35%447%29%
2520
16th to endDay
19%6%26%5%36%6%6%9%29%
2520
July1st to 15thDay
14%5%25%6%36%5%6%8%35%
2520
16th to endDay
13%5%26%5%35%7%7%8%33%
2654
August1st to 15thDay
12%7%36%6%35%6%6%8%34%
2490
16th to endDay
11%4245%45%45%8%43%
2303
September1st to 15thDay
17%6%2442446%6%41%
2160
16th to endDay
16%5%24322337%48%
2010
October1st to 15thDay
21%8%26%42425%435%
1806
16th to endDay
25%10%37%6%3435%424%
1785
November1st to 15thDay
17%7%46%6%246%5%5%32%
1693
16th to endDay
25%10%46%6%23445%26%
1558
December1st to 15thDay
26%14%5%6%435%435%18%
1440
16th to endDay
25%16%6%8%5%2432320%
1536
January1st to 15thNight
19%16%5%8%7%35%44419%
2506
16th to endNight
13%15%5%9%7%45%44425%
2685
February1st to 15thNight
13%13%6%10%8%35%46%5%22%
2278
16th to endNight
16%12%5%8%6%35%44427%
1916
March1st to 15thNight
21%10%47%7%24435%27%
2144
16th to endNight
16%10%35%5%3333441%
2004
April1st to 15thNight
25%8%345%23346%33%
1796
16th to endNight
21%7%245%2334438%
1728
May1st to 15thNight
22%6%36%5%23345%35%
1440
16th to endNight
18%6%35%5%24347%38%
1495
June1st to 15thNight
23%6%36%4345%47%30%
1440
16th to endNight
16%5%36%326%6%5%7%36%
1440
July1st to 15thNight
10%5%245%245%6%9%43%
1440
16th to endNight
10%5%245%25%5%6%8%42%
1514
August1st to 15thNight
12%4345%35%5%7%9%38%
1469
16th to endNight
10%424434447%48%
1887
September1st to 15thNight
16%5%25%5%34447%41%
1800
16th to endNight
17%413323346%48%
1949
October1st to 15thNight
19%7%25%42435%6%38%
2154
16th to endNight
24%10%36%6%33345%28%
2439
November1st to 15thNight
21%8%36%5%34345%33%
2492
16th to endNight
21%11%5%9%6%24445%25%
2728
December1st to 15thNight
22%14%5%8%5%35%43421%
2520
16th to endNight
24%17%47%5%3433421%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
69%5%7%12%4
1433
16th to endDay
60%6%10%13%8%
1536
February1st to 15thDay
61%5%9%17%5%
1577
16th to endDay
61%49%13%9%1
1557
March1st to 15thDay
60%5%10%13%8%1
1815
16th to endDay
48%49%17%15%4
2220
April1st to 15thDay
53%38%19%12%2
2152
16th to endDay
51%5%7%18%13%4
2244
May1st to 15thDay
53%5%7%18%13%1
2511
16th to endDay
49%7%11%18%11%1
2622
June1st to 15thDay
54%6%10%18%9%
2520
16th to endDay
49%9%11%18%9%
2520
July1st to 15thDay
41%8%14%24%11%
2371
16th to endDay
44%11%15%20%8%
2487
August1st to 15thDay
45%10%15%20%7%
2476
16th to endDay
36%7%17%26%10%
2303
September1st to 15thDay
41%6%14%25%11%
2160
16th to endDay
37%5%13%32%10%
2010
October1st to 15thDay
51%5%11%21%10%
1806
16th to endDay
61%7%12%13%5%
1785
November1st to 15thDay
50%8%14%16%8%
1693
16th to endDay
59%6%11%14%6%
1558
December1st to 15thDay
67%7%12%9%3
1440
16th to endDay
68%5%9%9%6%
1536
January1st to 15thNight
67%6%9%12%3
2506
16th to endNight
60%5%10%15%6%1
2685
February1st to 15thNight
61%5%10%16%4
2287
16th to endNight
58%5%9%15%10%
1916
March1st to 15thNight
58%5%9%16%8%1
2144
16th to endNight
47%39%19%15%4
2004
April1st to 15thNight
52%47%19%13%1
1796
16th to endNight
49%48%17%16%3
1728
May1st to 15thNight
50%5%7%17%14%4
1440
16th to endNight
45%7%10%20%14%1
1497
June1st to 15thNight
54%6%10%19%9%
1440
16th to endNight
43%9%11%19%15%
1440
July1st to 15thNight
34%8%13%28%14%
1360
16th to endNight
36%8%16%24%13%
1418
August1st to 15thNight
39%10%16%23%9%
1459
16th to endNight
34%5%17%30%11%
1887
September1st to 15thNight
43%6%13%23%12%
1800
16th to endNight
36%6%11%32%12%
1949
October1st to 15thNight
46%5%11%24%11%
2154
16th to endNight
57%5%13%17%6%
2439
November1st to 15thNight
52%5%13%17%8%1
2492
16th to endNight
61%6%10%16%4
2728
December1st to 15thNight
65%6%10%14%2
2520
16th to endNight
67%5%9%11%6%
2688

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
28%26%23%13%8%
60
16th to endDay
34%15%32%10%6%
64
February1st to 15thDay
30%31%32%6%
90
16th to endDay
29%19%28%20%2
216
March1st to 15thDay
24%20%31%20%4
270
16th to endDay
23%16%29%18%8%3
288
April1st to 15thDay
28%22%25%15%6%1
270
16th to endDay
24%19%27%19%8%1
270
May1st to 15thDay
27%16%28%19%6%2
288
16th to endDay
24%16%32%18%8%
331
June1st to 15thDay
24%12%34%19%7%
315
16th to endDay
21%10%33%24%7%1
315
July1st to 15thDay
16%10%31%24%13%3
305
16th to endDay
16%5%28%31%14%3
326
August1st to 15thDay
16%6%25%35%11%4
313
16th to endDay
15%7%25%24%17%9%
332
September1st to 15thDay
20%7%21%22%20%7%
315
16th to endDay
16%12%19%20%21%9%
314
October1st to 15thDay
25%12%21%23%13%2
315
16th to endDay
31%18%23%18%6%
302
November1st to 15thDay
22%15%28%26%6%
257
16th to endDay
31%24%27%13%3
90
December1st to 15thDay
30%20%31%15%3
60
16th to endDay
39%25%32%11
64
January1st to 15thNight
29%14%32%19%4
720
16th to endNight
20%16%33%21%6%1
768
February1st to 15thNight
21%16%34%23%4
704
16th to endNight
23%18%31%21%4
631
March1st to 15thNight
26%15%33%20%4
720
16th to endNight
20%15%30%25%7%
768
April1st to 15thNight
27%13%29%25%3
718
16th to endNight
26%12%31%19%8%
648
May1st to 15thNight
23%9%30%25%8%1
360
16th to endNight
20%9%31%27%9%
375
June1st to 15thNight
25%8%26%31%8%
360
16th to endNight
18%428%32%13%1
360
July1st to 15thNight
11%7%24%36%19%
340
16th to endNight
13%324%37%19%1
376
August1st to 15thNight
15%318%38%21%1
388
16th to endNight
13%423%33%22%2
741
September1st to 15thNight
20%424%33%16%1
720
16th to endNight
18%8%21%27%20%3
717
October1st to 15thNight
23%10%26%27%11%
720
16th to endNight
30%11%27%24%5%
768
November1st to 15thNight
27%11%28%22%9%
760
16th to endNight
27%17%27%17%9%
780
December1st to 15thNight
31%16%28%20%3
720
16th to endNight
34%15%31%14%4
768
Page generated at 2017-12-01 12:13:43. Version ac04

Copyright 2017 A. Danko


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