Hawkesbury
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hawkesbury clear sky chart from 2005-11-06 to 2024-02-05.

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
27%
22613
8%
80501
5%
22527
32%
22527
8%
65551

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 10thNight
12%
755
5%
4400
1%
737
15%
737
2%
3541
January11th to 20thNight
15%
757
4%
4413
2%
740
18%
740
2%
3572
January21st to endNight
18%
827
4%
4873
4%
814
24%
814
4%
4104
February1st to 10thNight
15%
739
6%
2399
1%
739
21%
739
6%
2039
February11th to 20thNight
16%
703
7%
2221
2%
700
23%
700
6%
1894
February21st to endNight
18%
592
9%
1776
4%
592
25%
592
7%
1494
March1st to 10thNight
18%
720
9%
2160
4%
720
23%
720
7%
1816
March11th to 20thNight
19%
720
8%
2047
3%
720
24%
720
8%
1709
March21st to endNight
26%
792
13%
2016
5%
792
32%
792
11%
1628
April1st to 10thNight
22%
720
9%
1800
2%
720
25%
720
11%
1507
April11th to 20thNight
25%
711
11%
1775
3%
711
29%
711
12%
1437
April21st to endNight
23%
612
11%
1692
4%
612
28%
612
10%
1375
May1st to 10thNight
28%
360
10%
1440
6%
360
36%
360
8%
1110
May11th to 20thNight
31%
354
15%
1416
11%
354
43%
354
10%
1042
May21st to endNight
29%
389
10%
1551
8%
388
39%
388
10%
1163
June1st to 10thNight
31%
360
5%
1440
3%
360
38%
360
8%
1140
June11th to 20thNight
38%
360
8%
1440
9%
360
44%
360
10%
1096
June21st to endNight
40%
360
7%
1440
10%
360
44%
360
8%
1147
July1st to 10thNight
48%
350
8%
1400
11%
350
52%
350
11%
1032
July11th to 20thNight
50%
348
9%
1392
13%
348
53%
348
11%
1039
July21st to endNight
48%
394
8%
1486
9%
372
51%
372
10%
1125
August1st to 10thNight
54%
358
8%
1422
7%
356
58%
356
10%
1078
August11th to 20thNight
52%
542
13%
1606
9%
542
55%
542
17%
1194
August21st to endNight
47%
792
9%
1980
4%
792
49%
792
17%
1580
September1st to 10thNight
44%
720
8%
1800
3%
720
46%
720
17%
1427
September11th to 20thNight
50%
720
13%
1842
7%
720
53%
720
17%
1422
September21st to endNight
43%
720
11%
1980
8%
720
45%
720
14%
1567
October1st to 10thNight
33%
720
11%
2149
6%
720
39%
720
11%
1719
October11th to 20thNight
26%
720
9%
2163
5%
720
32%
720
8%
1805
October21st to endNight
23%
792
7%
2574
4%
792
27%
792
8%
2143
November1st to 10thNight
26%
740
9%
2407
6%
740
32%
740
9%
1944
November11th to 20thNight
19%
760
11%
2593
7%
760
25%
760
7%
2136
November21st to endNight
17%
760
6%
2660
3%
760
21%
760
4%
2306
December1st to 10thNight
13%
760
3%
2660
1%
760
16%
760
3%
2396
December11th to 20thNight
14%
760
8%
3244
3%
759
20%
759
3%
2714
December21st to endNight
10%
826
4%
4844
1%
817
14%
817
2%
4110

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
18%10%47%6%35%45%6%31%
78040
Night
18%11%47%6%34446%31%
80819
TransparencyDay
35%38%8%12%6%1
77745
Night
37%36%9%11%5%1
80648
SeeingDay
25%17%30%19%8%2
13455
Night
24%14%29%24%8%1
22640

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 10thDay
17%19%7%12%8%3444419%
2517
11th to 20thDay
15%14%6%10%9%35%5%5%6%21%
2520
21st to endDay
14%20%7%9%6%37%6%45%19%
2772
February1st to 10thDay
14%16%5%10%8%35%446%24%
1656
11th to 20thDay
14%16%6%10%6%4445%6%26%
1627
21st to endDay
19%15%5%8%8%35%35%5%25%
1480
March1st to 10thDay
16%13%5%9%7%35%345%29%
1797
11th to 20thDay
15%13%49%6%45%45%5%31%
1912
21st to endDay
21%9%46%5%34445%35%
2340
April1st to 10thDay
22%12%47%434335%33%
2160
11th to 20thDay
21%9%36%5%34445%35%
2134
21st to endDay
24%10%37%5%34446%30%
2285
May1st to 10thDay
21%7%37%6%35%45%6%33%
2520
11th to 20thDay
19%7%36%5%35%446%37%
2478
21st to endDay
18%6%36%5%35%5%6%7%36%
2725
June1st to 10thDay
23%7%36%5%345%5%8%29%
2520
11th to 20thDay
16%6%246%46%5%6%8%36%
2520
21st to endDay
22%6%36%6%46%5%6%7%29%
2520
July1st to 10thDay
13%5%35%7%45%6%6%8%38%
2520
11th to 20thDay
14%6%26%6%45%6%7%10%34%
2520
21st to endDay
13%6%36%6%45%6%7%9%35%
2744
August1st to 10thDay
13%7%36%6%45%6%6%8%36%
2506
11th to 20thDay
13%6%36%5%45%5%6%8%39%
2275
21st to endDay
14%7%35%5%35%5%6%8%41%
2376
September1st to 10thDay
16%5%345%35%5%6%7%41%
2160
11th to 20thDay
15%5%2432445%7%48%
2117
21st to endDay
20%6%35%32446%7%41%
1980
October1st to 10thDay
23%8%25%6%3445%6%35%
1810
11th to 20thDay
24%10%37%6%35%45%5%27%
1796
21st to endDay
26%10%47%7%3435%5%25%
1782
November1st to 10thDay
18%9%46%5%35%5%5%7%32%
1671
11th to 20thDay
22%11%5%8%5%45%5%5%6%25%
1582
21st to endDay
22%14%48%7%35%446%24%
1520
December1st to 10thDay
25%15%6%9%5%45%446%17%
1520
11th to 20thDay
22%14%6%9%5%35%445%24%
1906
21st to endDay
26%20%6%8%6%3343319%
2772
January1st to 10thNight
18%17%7%10%6%34445%22%
4429
11th to 20thNight
13%15%6%12%8%45%5%5%5%21%
4440
21st to endNight
15%18%7%10%8%44435%22%
4880
February1st to 10thNight
15%14%7%10%7%45%45%6%24%
2399
11th to 20thNight
15%11%6%10%8%45%45%5%28%
2219
21st to endNight
17%13%5%9%6%345%45%30%
1776
March1st to 10thNight
17%12%5%10%7%345%45%29%
2150
11th to 20thNight
18%14%5%6%5%35%445%31%
2046
21st to endNight
18%9%46%5%44345%39%
2016
April1st to 10thNight
23%9%45%6%25%347%32%
1800
11th to 20thNight
21%7%37%5%34446%36%
1775
21st to endNight
22%9%36%5%35%445%35%
1692
May1st to 10thNight
21%7%36%6%245%5%6%35%
1440
11th to 20thNight
19%6%35%42345%7%41%
1415
21st to endNight
16%7%345%2445%7%41%
1550
June1st to 10thNight
20%6%35%6%35%6%5%9%31%
1440
11th to 20thNight
16%7%36%425%5%5%7%39%
1440
21st to endNight
18%7%25%6%35%6%5%7%36%
1440
July1st to 10thNight
11%6%26%4435%5%8%45%
1440
11th to 20thNight
12%6%35%5%35%46%11%41%
1440
21st to endNight
12%5%35%5%36%5%6%7%42%
1574
August1st to 10thNight
12%6%25%5%35%6%6%9%41%
1432
11th to 20thNight
12%6%25%5%35%5%7%7%45%
1606
21st to endNight
14%5%25%6%35%45%8%44%
1980
September1st to 10thNight
14%5%35%5%445%5%7%44%
1800
11th to 20thNight
17%5%2442345%7%48%
1842
21st to endNight
18%6%244345%5%6%44%
1980
October1st to 10thNight
20%6%35%5%35%45%6%37%
2149
11th to 20thNight
22%9%37%6%35%446%33%
2163
21st to endNight
24%9%47%7%43445%29%
2574
November1st to 10thNight
21%10%36%6%3445%6%32%
2407
11th to 20thNight
19%10%48%7%35%445%31%
2593
21st to endNight
22%13%48%6%35%5%45%25%
2660
December1st to 10thNight
21%16%6%9%7%35%445%19%
2660
11th to 20thNight
23%15%5%8%6%3444425%
3288
21st to endNight
28%19%48%5%3333320%
4884

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 10thDay
50%31%7%8%31
2518
11th to 20thDay
45%30%10%11%31
2520
21st to endDay
52%28%9%6%4
2772
February1st to 10thDay
40%36%7%11%41
1656
11th to 20thDay
39%39%8%9%31
1636
21st to endDay
42%37%6%10%5%
1480
March1st to 10thDay
38%38%7%11%5%1
1800
11th to 20thDay
37%37%11%10%5%
1912
21st to endDay
33%37%7%11%9%2
2340
April1st to 10thDay
36%37%7%13%7%2
2160
11th to 20thDay
34%37%6%13%9%1
2134
21st to endDay
36%38%5%9%8%3
2285
May1st to 10thDay
33%38%5%11%10%3
2520
11th to 20thDay
31%38%6%13%9%2
2482
21st to endDay
28%39%8%12%11%2
2725
June1st to 10thDay
35%39%8%10%7%
2520
11th to 20thDay
28%40%8%14%8%2
2520
21st to endDay
36%40%8%10%5%
2520
July1st to 10thDay
27%41%9%16%6%
2450
11th to 20thDay
29%41%10%13%7%
2445
21st to endDay
27%42%11%13%7%
2591
August1st to 10thDay
31%39%10%15%5%
2492
11th to 20thDay
24%40%13%17%6%
2275
21st to endDay
27%39%11%14%9%1
2376
September1st to 10thDay
26%39%10%18%7%
2160
11th to 20thDay
25%38%10%18%9%
2117
21st to endDay
30%39%10%17%5%
1980
October1st to 10thDay
33%38%8%14%6%
1810
11th to 20thDay
39%39%7%10%4
1796
21st to endDay
38%39%8%10%5%1
1782
November1st to 10thDay
27%43%11%15%5%
1671
11th to 20thDay
36%42%9%6%6%
1582
21st to endDay
39%43%8%8%2
1520
December1st to 10thDay
46%41%7%42
1520
11th to 20thDay
43%35%11%9%2
1906
21st to endDay
56%26%6%9%3
2772
January1st to 10thNight
49%29%13%7%2
4429
11th to 20thNight
46%32%12%8%2
4440
21st to endNight
53%27%9%7%4
4880
February1st to 10thNight
41%37%7%10%5%1
2399
11th to 20thNight
39%39%8%10%3
2221
21st to endNight
40%37%7%11%5%1
1776
March1st to 10thNight
39%37%7%12%5%1
2160
11th to 20thNight
38%37%9%11%41
2047
21st to endNight
32%36%6%13%9%3
2016
April1st to 10thNight
35%38%7%11%7%2
1800
11th to 20thNight
32%37%7%14%9%1
1775
21st to endNight
34%37%6%12%8%3
1692
May1st to 10thNight
32%38%6%10%10%4
1440
11th to 20thNight
27%38%7%13%12%3
1416
21st to endNight
27%40%8%12%12%2
1551
June1st to 10thNight
32%40%10%13%5%
1440
11th to 20thNight
30%38%9%13%9%1
1440
21st to endNight
31%41%8%10%9%
1440
July1st to 10thNight
24%41%10%18%7%
1400
11th to 20thNight
25%41%11%15%8%
1392
21st to endNight
26%41%10%13%9%
1486
August1st to 10thNight
27%40%11%16%6%
1422
11th to 20thNight
22%39%12%19%7%
1606
21st to endNight
26%40%12%15%7%1
1980
September1st to 10thNight
27%39%10%15%9%1
1800
11th to 20thNight
25%38%9%21%7%
1842
21st to endNight
28%39%10%16%7%
1980
October1st to 10thNight
32%38%9%13%8%
2149
11th to 20thNight
36%39%9%12%5%
2163
21st to endNight
37%38%9%10%5%1
2574
November1st to 10thNight
30%43%9%13%5%
2407
11th to 20thNight
34%41%8%9%6%1
2593
21st to endNight
39%42%7%9%2
2660
December1st to 10thNight
44%42%6%7%1
2660
11th to 20thNight
43%34%7%13%3
3288
21st to endNight
54%27%6%10%2
4884

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 10thDay
26%23%31%17%3
180
11th to 20thDay
31%18%36%9%6%
180
21st to endDay
23%18%37%17%5%
198
February1st to 10thDay
37%27%31%5%1
252
11th to 20thDay
25%30%36%8%
294
21st to endDay
32%25%27%14%2
346
March1st to 10thDay
27%22%32%17%2
420
11th to 20thDay
29%22%30%13%41
420
21st to endDay
31%19%26%16%6%1
462
April1st to 10thDay
31%20%29%15%5%1
420
11th to 20thDay
33%18%23%17%8%1
412
21st to endDay
33%19%31%11%5%1
420
May1st to 10thDay
25%22%31%16%5%1
423
11th to 20thDay
22%22%30%20%6%1
447
21st to endDay
23%17%33%19%6%1
485
June1st to 10thDay
25%16%34%17%8%
450
11th to 20thDay
18%16%33%22%10%2
450
21st to endDay
24%15%31%20%8%2
450
July1st to 10thDay
15%10%34%26%12%3
445
11th to 20thDay
17%10%35%26%11%1
444
21st to endDay
17%9%34%29%11%1
488
August1st to 10thDay
17%8%29%33%10%3
446
11th to 20thDay
16%8%27%29%14%6%
439
21st to endDay
17%14%28%21%15%6%
495
September1st to 10thDay
19%9%31%23%13%4
450
11th to 20thDay
14%13%27%21%18%7%
450
21st to endDay
21%14%25%22%14%4
450
October1st to 10thDay
26%17%22%20%11%2
450
11th to 20thDay
28%21%26%17%7%1
448
21st to endDay
34%13%31%17%4
396
November1st to 10thDay
31%15%27%22%5%1
365
11th to 20thDay
27%23%34%13%3
242
21st to endDay
32%20%31%16%2
180
December1st to 10thDay
35%13%32%16%31
180
11th to 20thDay
29%27%30%12%2
180
21st to endDay
35%19%30%11%41
198
January1st to 10thNight
29%14%34%19%3
760
11th to 20thNight
29%19%30%17%5%
760
21st to endNight
19%17%36%22%5%1
836
February1st to 10thNight
22%20%33%21%4
739
11th to 20thNight
24%19%35%18%4
703
21st to endNight
25%18%32%22%3
592
March1st to 10thNight
24%17%35%20%4
720
11th to 20thNight
25%20%31%18%5%
720
21st to endNight
24%16%30%24%6%1
792
April1st to 10thNight
30%14%28%24%4
720
11th to 20thNight
25%15%32%21%6%
711
21st to endNight
29%14%30%20%8%
612
May1st to 10thNight
23%14%30%25%6%2
360
11th to 20thNight
21%12%31%27%8%1
354
21st to endNight
18%10%37%26%9%
389
June1st to 10thNight
23%8%31%30%9%
360
11th to 20thNight
20%8%29%32%10%1
360
21st to endNight
20%5%28%33%13%1
360
July1st to 10thNight
11%10%27%35%17%1
350
11th to 20thNight
12%6%25%39%17%1
348
21st to endNight
14%427%37%16%1
394
August1st to 10thNight
15%420%42%18%1
358
11th to 20thNight
14%322%35%24%2
542
21st to endNight
16%7%24%34%18%2
792
September1st to 10thNight
16%6%30%33%14%1
720
11th to 20thNight
18%8%20%31%20%2
720
21st to endNight
20%10%24%28%16%2
720
October1st to 10thNight
23%11%28%26%11%
720
11th to 20thNight
27%13%28%25%7%1
720
21st to endNight
29%13%29%24%4
792
November1st to 10thNight
27%13%28%24%7%1
740
11th to 20thNight
26%17%31%17%8%
760
21st to endNight
32%16%29%18%6%
760
December1st to 10thNight
30%18%31%18%4
760
11th to 20thNight
29%20%29%17%41
760
21st to endNight
35%17%29%15%4
836
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