Geraldton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Geraldton clear sky chart from 2005-11-05 to 2018-11-30.

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
27%
17256
10%
51698
5%
17210
31%
17210
14%
39363

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
18%
975
8%
2796
3%
970
23%
970
9%
2310
January16th to endNight
20%
1040
7%
2912
2%
1040
25%
1040
8%
2489
February1st to 15thNight
28%
954
10%
2647
5%
950
33%
950
16%
2025
February16th to endNight
28%
688
12%
2054
6%
688
32%
688
13%
1572
March1st to 15thNight
30%
780
14%
2340
9%
780
35%
780
16%
1706
March16th to endNight
30%
716
18%
2195
11%
716
39%
716
19%
1534
April1st to 15thNight
29%
584
13%
1934
8%
584
36%
584
16%
1388
April16th to endNight
34%
579
15%
1735
8%
579
40%
579
22%
1177
May1st to 15thNight
28%
585
11%
1561
5%
585
33%
585
20%
1150
May16th to endNight
30%
469
9%
1484
6%
468
35%
468
17%
1069
June1st to 15thNight
36%
390
5%
1365
4%
390
40%
390
19%
911
June16th to endNight
33%
390
4%
1365
4%
390
35%
390
18%
907
July1st to 15thNight
40%
388
6%
1313
4%
388
43%
388
26%
786
July16th to endNight
43%
612
10%
1545
5%
579
45%
579
29%
1027
August1st to 15thNight
45%
575
15%
1526
6%
572
51%
572
29%
995
August16th to endNight
37%
621
16%
1903
10%
621
43%
621
24%
1255
September1st to 15thNight
39%
595
14%
1960
8%
595
47%
595
24%
1248
September16th to endNight
28%
777
12%
2145
7%
777
32%
777
19%
1579
October1st to 15thNight
23%
780
10%
2311
4%
780
28%
780
14%
1766
October16th to endNight
20%
832
6%
2704
3%
832
24%
832
8%
2247
November1st to 15thNight
17%
861
9%
2710
4%
861
22%
861
7%
2262
November16th to endNight
17%
1050
6%
3148
3%
1050
20%
1050
7%
2706
December1st to 15thNight
17%
975
4%
2925
1%
975
20%
975
6%
2559
December16th to endNight
19%
1040
8%
3120
5%
1040
22%
1040
7%
2695

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
17%11%47%6%35%45%6%27%
52620
Night
15%12%48%6%45%5%5%6%26%
51857
Cloud CoverDay
17%11%47%6%35%45%6%27%
52630
Night
15%11%48%6%35%5%5%6%26%
51862
TransparencyDay
56%6%10%18%7%
52296
Night
57%6%10%17%6%
51699
SeeingDay
23%12%32%19%8%3
7692
Night
21%10%31%24%9%1
17257

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
12%13%7%10%9%5%7%6%9%5%12%
1470
16th to endDay
12%14%411%9%5%8%9%7%7%10%
1664
February1st to 15thDay
6%12%49%8%5%8%7%7%7%21%
1544
16th to endDay
7%12%5%11%8%48%45%6%24%
1705
March1st to 15thDay
12%13%5%8%7%45%6%46%26%
1940
16th to endDay
13%11%46%6%35%445%31%
2392
April1st to 15thDay
12%12%47%7%3445%5%31%
2344
16th to endDay
17%12%46%423245%34%
2500
May1st to 15thDay
23%8%36%6%34446%27%
2718
16th to endDay
23%8%25%5%3445%7%30%
2982
June1st to 15thDay
22%8%25%5%3345%5%33%
2925
16th to endDay
18%7%26%5%34447%34%
2925
July1st to 15thDay
19%5%36%43445%8%35%
2902
16th to endDay
16%5%245%35%47%8%36%
2879
August1st to 15thDay
16%5%25%6%35%5%6%8%33%
2678
16th to endDay
18%6%26%43445%7%36%
2647
September1st to 15thDay
19%8%26%434445%36%
2317
16th to endDay
25%11%35%424336%28%
2145
October1st to 15thDay
22%16%36%4235%46%24%
1976
16th to endDay
24%22%6%6%6%3433413%
1872
November1st to 15thDay
18%18%7%12%7%3442415%
1807
16th to endDay
19%18%7%10%9%45%34413%
1467
December1st to 15thDay
12%16%6%12%11%5%7%6%5%5%8%
1365
16th to endDay
13%17%8%14%8%5%6%45%5%10%
1456
January1st to 15thNight
12%16%5%10%7%48%8%7%6%12%
2796
16th to endNight
11%14%5%11%9%6%10%8%6%5%10%
2912
February1st to 15thNight
7%10%48%7%6%9%9%6%7%22%
2644
16th to endNight
8%12%6%9%8%5%7%6%6%5%23%
2054
March1st to 15thNight
10%10%5%9%7%46%45%7%30%
2327
16th to endNight
11%10%47%8%34435%36%
2195
April1st to 15thNight
13%10%47%6%35%5%6%6%29%
1934
16th to endNight
17%9%2442345%6%37%
1735
May1st to 15thNight
21%9%35%42435%6%33%
1561
16th to endNight
23%7%25%423346%34%
1483
June1st to 15thNight
19%5%24425%5%5%6%36%
1365
16th to endNight
16%7%35%435%45%6%37%
1365
July1st to 15thNight
13%5%2433346%8%44%
1384
16th to endNight
10%5%25%425%46%9%42%
1641
August1st to 15thNight
9%5%26%425%45%8%44%
1535
16th to endNight
13%5%26%5%2445%7%41%
1903
September1st to 15thNight
15%6%25%5%2335%6%44%
1960
16th to endNight
26%6%34423445%34%
2145
October1st to 15thNight
22%15%35%5%33335%29%
2311
16th to endNight
22%18%49%5%34445%17%
2704
November1st to 15thNight
20%17%7%9%7%35%445%16%
2710
16th to endNight
18%16%6%11%9%45%44414%
3148
December1st to 15thNight
12%17%7%12%9%6%8%6%449%
2925
16th to endNight
15%17%6%11%9%5%7%5%45%11%
3120

Percentage Cloud Cover SW (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
12%14%7%10%9%47%6%8%5%12%
1470
16th to endDay
12%14%410%9%5%9%8%7%7%10%
1664
February1st to 15thDay
6%12%49%9%5%8%6%6%7%22%
1544
16th to endDay
7%12%6%11%8%47%45%6%25%
1705
March1st to 15thDay
12%13%48%7%45%6%46%26%
1950
16th to endDay
14%11%5%6%6%34445%31%
2392
April1st to 15thDay
12%12%5%7%7%3445%5%31%
2344
16th to endDay
17%12%46%423346%34%
2500
May1st to 15thDay
22%9%36%6%34446%27%
2718
16th to endDay
23%8%25%5%2445%6%30%
2982
June1st to 15thDay
21%8%25%5%34446%33%
2925
16th to endDay
18%6%36%5%24447%34%
2925
July1st to 15thDay
18%5%25%5%3445%8%35%
2902
16th to endDay
16%5%245%35%46%8%36%
2879
August1st to 15thDay
16%5%35%5%45%6%6%8%33%
2678
16th to endDay
18%6%25%5%3445%7%35%
2647
September1st to 15thDay
19%8%25%5%34446%36%
2317
16th to endDay
25%12%35%424335%28%
2145
October1st to 15thDay
22%16%26%42345%6%24%
1976
16th to endDay
24%21%6%8%5%33345%13%
1872
November1st to 15thDay
19%18%7%11%7%3433415%
1807
16th to endDay
19%18%6%11%9%35%34413%
1467
December1st to 15thDay
11%17%6%12%10%5%8%6%5%6%8%
1365
16th to endDay
13%17%8%14%8%5%6%46%410%
1456
January1st to 15thNight
12%16%6%10%8%48%7%8%5%12%
2796
16th to endNight
11%14%5%11%9%5%10%7%6%5%10%
2912
February1st to 15thNight
7%10%48%7%5%10%8%6%7%23%
2637
16th to endNight
8%13%6%9%8%47%7%5%6%22%
2054
March1st to 15thNight
10%10%5%9%7%45%45%6%30%
2340
16th to endNight
11%10%48%7%44445%36%
2195
April1st to 15thNight
13%11%47%6%35%5%6%5%29%
1934
16th to endNight
17%10%2441435%6%37%
1735
May1st to 15thNight
21%9%25%42435%6%33%
1560
16th to endNight
22%8%24424346%34%
1483
June1st to 15thNight
19%6%244245%6%6%36%
1365
16th to endNight
17%6%26%4245%5%6%36%
1365
July1st to 15thNight
14%42433346%8%44%
1384
16th to endNight
10%5%25%435%5%6%8%42%
1641
August1st to 15thNight
9%5%26%43445%9%44%
1535
16th to endNight
13%5%26%5%2345%8%41%
1903
September1st to 15thNight
15%6%2442335%6%43%
1960
16th to endNight
26%7%24423446%34%
2145
October1st to 15thNight
22%14%25%5%23335%29%
2311
16th to endNight
22%17%5%8%5%3445%6%16%
2704
November1st to 15thNight
20%16%6%9%7%2444416%
2710
16th to endNight
18%16%6%12%9%45%43414%
3148
December1st to 15thNight
12%16%7%11%10%7%8%6%449%
2925
16th to endNight
15%17%6%11%10%5%7%5%45%11%
3120

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
68%410%12%3
1471
16th to endDay
68%7%8%11%3
1664
February1st to 15thDay
57%5%10%19%5%
1545
16th to endDay
59%49%19%6%
1705
March1st to 15thDay
57%5%9%15%10%1
1950
16th to endDay
53%5%9%18%11%1
2392
April1st to 15thDay
53%49%21%9%1
2344
16th to endDay
51%5%8%19%15%1
2500
May1st to 15thDay
56%5%8%18%9%1
2718
16th to endDay
53%6%12%18%8%
2986
June1st to 15thDay
52%5%8%19%13%
2925
16th to endDay
48%6%11%24%8%
2925
July1st to 15thDay
44%6%12%24%10%
2744
16th to endDay
44%8%13%25%6%
2712
August1st to 15thDay
45%9%16%20%7%
2663
16th to endDay
46%8%13%23%8%
2647
September1st to 15thDay
48%6%15%21%7%
2317
16th to endDay
58%5%12%18%4
2145
October1st to 15thDay
58%6%13%16%3
1976
16th to endDay
74%5%9%10%
1872
November1st to 15thDay
73%5%9%10%1
1807
16th to endDay
74%49%7%3
1467
December1st to 15thDay
74%6%7%9%1
1365
16th to endDay
74%46%10%3
1456
January1st to 15thNight
68%5%9%13%3
2796
16th to endNight
71%5%7%11%4
2912
February1st to 15thNight
55%7%11%19%5%
2647
16th to endNight
59%5%10%18%6%
2054
March1st to 15thNight
54%5%9%20%10%
2340
16th to endNight
50%5%9%20%12%2
2195
April1st to 15thNight
52%6%8%18%12%1
1934
16th to endNight
45%5%11%19%14%2
1735
May1st to 15thNight
51%5%7%21%11%1
1561
16th to endNight
50%7%10%20%9%
1485
June1st to 15thNight
44%8%10%24%11%
1365
16th to endNight
45%7%12%24%8%
1365
July1st to 15thNight
34%8%15%26%14%
1313
16th to endNight
37%8%15%28%8%
1545
August1st to 15thNight
36%8%18%28%7%
1526
16th to endNight
39%8%15%26%8%
1903
September1st to 15thNight
40%7%17%27%7%
1960
16th to endNight
51%6%16%19%5%
2145
October1st to 15thNight
58%5%14%16%4
2311
16th to endNight
67%7%10%12%2
2704
November1st to 15thNight
69%6%8%10%3
2710
16th to endNight
73%5%8%8%3
3148
December1st to 15thNight
75%5%8%8%2
2925
16th to endNight
74%46%9%4
3120

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
17%12%38%19%10%
116
16th to endDay
22%12%36%16%7%4
144
February1st to 15thDay
16%17%40%22%2
135
16th to endDay
21%26%38%11%1
120
March1st to 15thDay
16%19%31%20%11%
135
16th to endDay
19%11%42%14%7%4
329
April1st to 15thDay
17%16%32%23%7%2
330
16th to endDay
25%10%30%20%7%5%
319
May1st to 15thDay
27%15%33%14%6%1
540
16th to endDay
28%13%30%18%6%2
597
June1st to 15thDay
29%11%27%18%10%3
570
16th to endDay
21%14%31%20%9%3
570
July1st to 15thDay
19%11%35%21%9%2
550
16th to endDay
14%10%32%25%12%4
595
August1st to 15thDay
17%9%32%22%11%6%
549
16th to endDay
23%7%31%20%13%4
410
September1st to 15thDay
20%12%28%22%12%4
375
16th to endDay
36%11%25%15%8%1
374
October1st to 15thDay
33%14%25%18%6%1
258
16th to endDay
34%16%36%9%11
192
November1st to 15thDay
31%16%30%16%31
179
16th to endDay
31%11%32%19%4
119
December1st to 15thDay
37%6%32%12%6%4
90
16th to endDay
17%16%35%16%10%3
96
January1st to 15thNight
21%14%34%21%6%
975
16th to endNight
18%14%34%23%7%1
1040
February1st to 15thNight
13%9%39%28%8%1
955
16th to endNight
14%9%36%28%9%1
688
March1st to 15thNight
16%14%31%25%10%1
780
16th to endNight
17%11%33%24%10%2
716
April1st to 15thNight
18%11%34%26%8%1
584
16th to endNight
21%7%31%27%9%1
579
May1st to 15thNight
27%9%30%25%7%
585
16th to endNight
26%7%29%28%6%1
469
June1st to 15thNight
22%6%30%28%11%
390
16th to endNight
20%7%34%27%9%
390
July1st to 15thNight
15%8%32%31%10%1
388
16th to endNight
13%6%32%30%16%
612
August1st to 15thNight
12%6%28%32%17%2
575
16th to endNight
15%7%33%27%16%
621
September1st to 15thNight
18%6%30%29%12%1
595
16th to endNight
30%9%29%22%8%
777
October1st to 15thNight
32%12%28%21%5%
780
16th to endNight
31%10%27%18%11%1
832
November1st to 15thNight
29%13%29%18%6%
861
16th to endNight
29%13%29%21%5%
1050
December1st to 15thNight
22%12%32%22%8%1
975
16th to endNight
23%10%31%20%10%3
1040
Page generated at 2018-12-01 11:35:38. Version ac04

Copyright 2018 A. Danko


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