Melville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Melville clear sky chart from 2005-11-06 to 2024-01-11.

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
37%
24672
13%
74168
8%
24626
43%
24626
21%
50530

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
29%
947
12%
2796
7%
946
34%
946
16%
2043
January11th to 20thNight
26%
905
10%
2533
4%
905
31%
905
15%
1970
January21st to endNight
22%
990
12%
2772
4%
990
29%
990
12%
2214
February1st to 10thNight
32%
900
13%
2520
5%
900
39%
900
18%
1853
February11th to 20thNight
34%
762
15%
2308
8%
762
41%
762
19%
1627
February21st to endNight
42%
592
21%
1776
12%
592
50%
592
21%
1227
March1st to 10thNight
34%
720
11%
2160
7%
720
37%
720
17%
1597
March11th to 20thNight
39%
689
17%
2129
10%
689
47%
689
22%
1437
March21st to endNight
40%
594
15%
1980
15%
594
45%
594
18%
1381
April1st to 10thNight
43%
540
18%
1800
16%
540
51%
540
27%
1098
April11th to 20thNight
36%
533
14%
1681
10%
533
43%
533
19%
1174
April21st to endNight
34%
540
13%
1545
7%
540
38%
540
22%
1076
May1st to 10thNight
44%
540
16%
1440
7%
540
47%
540
28%
949
May11th to 20thNight
45%
531
13%
1397
6%
531
48%
531
29%
938
May21st to endNight
42%
584
8%
1358
5%
582
44%
582
29%
969
June1st to 10thNight
40%
540
4%
1260
3%
540
43%
540
32%
869
June11th to 20thNight
39%
384
2%
1104
2%
384
40%
384
26%
739
June21st to endNight
50%
360
1%
1080
1%
360
51%
360
28%
684
July1st to 10thNight
59%
371
4%
1071
5%
371
61%
371
37%
615
July11th to 20thNight
53%
522
8%
1301
5%
522
56%
522
42%
784
July21st to endNight
67%
591
13%
1488
8%
558
68%
558
50%
801
August1st to 10thNight
62%
537
15%
1424
8%
534
66%
534
42%
828
August11th to 20thNight
61%
534
20%
1436
12%
534
65%
534
39%
842
August21st to endNight
54%
594
24%
1873
20%
594
62%
594
36%
1054
September1st to 10thNight
51%
540
19%
1800
18%
540
58%
540
31%
1029
September11th to 20thNight
48%
540
19%
1872
19%
540
53%
540
25%
1121
September21st to endNight
46%
540
22%
1980
18%
540
56%
540
27%
1120
October1st to 10thNight
42%
658
18%
2098
14%
658
47%
658
23%
1383
October11th to 20thNight
40%
847
19%
2287
9%
847
46%
847
27%
1520
October21st to endNight
30%
990
15%
2574
5%
990
36%
990
20%
1898
November1st to 10thNight
25%
925
14%
2447
5%
925
31%
925
16%
1879
November11th to 20thNight
26%
950
11%
2774
4%
950
32%
950
14%
2146
November21st to endNight
23%
950
11%
2850
4%
950
30%
950
14%
2125
December1st to 10thNight
26%
950
11%
2850
5%
950
33%
950
15%
2144
December11th to 20thNight
23%
950
10%
3469
3%
949
31%
949
9%
2694
December21st to endNight
31%
1032
9%
4935
7%
1026
38%
1026
12%
2702

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
11%8%47%6%45%5%6%7%36%
75042
Night
9%9%48%7%45%5%6%7%37%
74675
TransparencyDay
46%7%14%23%9%1
74730
Night
46%7%14%22%10%1
74505
SeeingDay
14%8%29%29%16%4
15064
Night
14%7%31%34%13%2
24692

By Month

Percentage Cloud Cover NW (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
9%13%6%9%9%47%7%7%10%19%
1367
11th to 20thDay
7%11%7%12%8%47%6%5%8%25%
1440
21st to endDay
8%14%7%11%9%49%6%6%6%20%
1584
February1st to 10thDay
8%13%5%11%8%5%7%8%5%7%24%
1440
11th to 20thDay
7%10%410%8%6%11%6%6%7%26%
1557
21st to endDay
5%10%5%11%9%6%6%7%7%8%26%
1480
March1st to 10thDay
11%13%6%11%9%5%7%5%6%7%20%
1800
11th to 20thDay
9%12%7%9%6%45%5%6%8%29%
1830
21st to endDay
10%11%6%9%7%5%5%5%5%7%30%
2376
April1st to 10thDay
9%10%5%8%6%45%5%5%7%37%
2160
11th to 20thDay
15%13%5%8%7%345%5%6%28%
2230
21st to endDay
13%8%37%6%35%5%5%8%36%
2412
May1st to 10thDay
13%7%37%5%35%5%5%7%40%
2520
11th to 20thDay
11%7%35%6%35%5%5%9%40%
2499
21st to endDay
20%7%36%6%445%5%8%33%
2918
June1st to 10thDay
16%6%25%5%35%5%8%8%37%
2700
11th to 20thDay
21%7%36%5%45%5%7%7%29%
2851
21st to endDay
14%5%246%46%6%6%9%38%
2880
July1st to 10thDay
8%315%5%35%5%8%9%48%
2856
11th to 20thDay
10%5%25%436%6%6%9%44%
2613
21st to endDay
7%425%5%346%7%8%50%
2742
August1st to 10thDay
8%435%5%45%5%7%9%46%
2507
11th to 20thDay
10%425%5%35%6%6%9%45%
2464
21st to endDay
13%5%25%425%45%7%49%
2480
September1st to 10thDay
12%425%436%45%8%47%
2160
11th to 20thDay
13%7%36%5%35%5%5%7%43%
2088
21st to endDay
13%7%35%5%33346%49%
1980
October1st to 10thDay
17%12%37%5%34446%36%
1859
11th to 20thDay
11%10%37%5%445%5%6%40%
1654
21st to endDay
11%11%6%10%6%45%5%5%6%31%
1782
November1st to 10thDay
18%14%5%9%6%45%446%25%
1627
11th to 20thDay
9%13%7%11%9%5%5%5%5%5%26%
1405
21st to endDay
10%16%7%9%7%435%46%29%
1330
December1st to 10thDay
8%11%6%11%10%5%6%6%6%7%23%
1330
11th to 20thDay
9%13%7%18%9%46%5%5%6%18%
1679
21st to endDay
5%8%46%5%45%35%7%49%
2442
January1st to 10thNight
5%12%6%10%8%45%6%7%8%28%
2796
11th to 20thNight
9%14%6%12%8%45%45%7%25%
2533
21st to endNight
6%13%7%12%10%5%7%7%6%7%20%
2772
February1st to 10thNight
9%10%49%9%46%6%7%7%29%
2520
11th to 20thNight
6%9%49%8%5%8%7%6%7%31%
2307
21st to endNight
49%410%9%5%7%6%47%36%
1776
March1st to 10thNight
10%11%5%10%8%5%5%5%6%7%30%
2160
11th to 20thNight
6%9%47%8%5%6%6%7%8%36%
2129
21st to endNight
8%9%410%7%47%5%5%7%34%
1980
April1st to 10thNight
6%7%46%6%45%5%6%8%44%
1800
11th to 20thNight
15%9%47%5%36%5%5%6%35%
1681
21st to endNight
16%8%46%5%445%5%7%36%
1545
May1st to 10thNight
12%7%36%5%35%5%6%7%41%
1440
11th to 20thNight
13%5%35%5%346%7%7%41%
1397
21st to endNight
19%5%345%345%6%9%37%
1358
June1st to 10thNight
13%6%36%5%345%5%9%42%
1260
11th to 20thNight
17%5%35%5%25%45%9%40%
1104
21st to endNight
11%5%25%5%346%6%9%45%
1080
July1st to 10thNight
7%42442447%7%54%
1102
11th to 20thNight
7%3145%2445%9%56%
1343
21st to endNight
6%322223349%63%
1576
August1st to 10thNight
5%323425%6%7%9%54%
1432
11th to 20thNight
8%414435%46%7%55%
1436
21st to endNight
9%5%2342445%7%54%
1873
September1st to 10thNight
9%5%245%3445%8%50%
1800
11th to 20thNight
11%6%36%5%3446%7%46%
1872
21st to endNight
11%6%35%33446%7%47%
1980
October1st to 10thNight
15%9%35%5%2446%8%40%
2098
11th to 20thNight
9%8%46%5%345%5%6%44%
2287
21st to endNight
12%12%5%9%5%45%5%5%6%33%
2574
November1st to 10thNight
15%12%48%9%35%45%6%29%
2447
11th to 20thNight
9%12%6%10%9%45%5%5%5%28%
2774
21st to endNight
9%11%6%11%8%45%5%5%7%29%
2850
December1st to 10thNight
7%10%6%11%9%5%6%5%6%7%27%
2850
11th to 20thNight
8%13%7%12%8%47%7%5%6%23%
3518
21st to endNight
6%7%38%6%45%6%5%5%46%
5225

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
59%8%11%15%7%
1367
11th to 20thDay
57%7%13%16%7%1
1440
21st to endDay
63%8%8%13%8%
1584
February1st to 10thDay
59%6%15%14%6%
1440
11th to 20thDay
54%7%10%18%11%
1566
21st to endDay
53%8%11%18%10%
1480
March1st to 10thDay
64%6%10%14%6%
1800
11th to 20thDay
54%7%13%18%8%
1831
21st to endDay
54%7%14%18%8%
2376
April1st to 10thDay
47%7%13%21%11%1
2160
11th to 20thDay
56%6%13%16%8%2
2230
21st to endDay
46%7%15%23%8%
2412
May1st to 10thDay
43%6%11%27%12%1
2520
11th to 20thDay
42%7%11%26%14%1
2503
21st to endDay
50%7%12%20%11%1
2918
June1st to 10thDay
41%8%15%25%9%1
2700
11th to 20thDay
51%8%14%18%8%1
2851
21st to endDay
41%9%18%25%7%
2880
July1st to 10thDay
29%10%21%32%8%
2778
11th to 20thDay
35%10%18%28%9%1
2532
21st to endDay
29%9%20%33%8%
2590
August1st to 10thDay
34%10%18%27%11%1
2491
11th to 20thDay
34%10%19%32%5%
2464
21st to endDay
35%7%14%33%11%
2480
September1st to 10thDay
35%7%14%31%12%1
2160
11th to 20thDay
41%6%15%26%11%1
2088
21st to endDay
38%5%13%31%12%1
1980
October1st to 10thDay
50%5%13%24%7%1
1859
11th to 20thDay
44%7%11%28%9%
1654
21st to endDay
55%6%14%19%6%
1782
November1st to 10thDay
61%5%11%16%7%1
1627
11th to 20thDay
61%6%13%13%6%1
1405
21st to endDay
58%6%13%19%5%
1330
December1st to 10thDay
59%8%12%15%6%
1330
11th to 20thDay
66%7%14%10%3
1680
21st to endDay
36%7%12%25%14%6%
2442
January1st to 10thNight
52%7%14%19%7%
2796
11th to 20thNight
59%6%13%14%7%
2533
21st to endNight
60%8%10%12%9%
2772
February1st to 10thNight
53%6%13%19%10%1
2520
11th to 20thNight
48%8%13%20%11%1
2308
21st to endNight
47%6%11%25%11%
1776
March1st to 10thNight
54%6%13%20%6%
2160
11th to 20thNight
44%8%14%25%8%1
2129
21st to endNight
49%7%13%19%11%1
1980
April1st to 10thNight
37%7%12%24%19%1
1800
11th to 20thNight
49%6%11%20%12%2
1681
21st to endNight
47%6%12%21%12%1
1545
May1st to 10thNight
40%6%11%26%17%1
1440
11th to 20thNight
40%8%9%24%17%2
1397
21st to endNight
44%6%15%22%12%1
1358
June1st to 10thNight
40%6%16%24%13%2
1260
11th to 20thNight
40%9%18%18%14%1
1104
21st to endNight
36%9%18%28%8%1
1080
July1st to 10thNight
27%8%20%32%13%
1071
11th to 20thNight
26%7%19%35%11%1
1301
21st to endNight
21%5%20%39%13%2
1488
August1st to 10thNight
24%9%21%34%12%
1424
11th to 20thNight
28%7%19%34%11%1
1436
21st to endNight
30%6%12%38%14%1
1873
September1st to 10thNight
32%7%14%31%14%2
1800
11th to 20thNight
36%8%15%27%13%1
1872
21st to endNight
35%5%13%31%14%2
1980
October1st to 10thNight
43%7%17%24%8%1
2098
11th to 20thNight
41%6%13%28%11%1
2287
21st to endNight
51%6%13%23%6%
2574
November1st to 10thNight
57%6%12%15%8%1
2447
11th to 20thNight
59%7%14%15%5%
2774
21st to endNight
55%7%16%17%5%
2850
December1st to 10thNight
56%7%13%17%6%1
2850
11th to 20thNight
61%7%12%13%6%
3516
21st to endNight
39%6%11%22%17%5%
5225

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
13%8%28%31%16%3
270
11th to 20thDay
7%7%37%37%10%3
240
21st to endDay
16%9%28%32%13%2
264
February1st to 10thDay
14%9%40%26%11%
240
11th to 20thDay
9%7%33%35%14%3
240
21st to endDay
8%5%28%37%17%5%
198
March1st to 10thDay
14%7%32%32%14%2
240
11th to 20thDay
13%10%32%28%15%3
240
21st to endDay
16%10%31%25%16%2
462
April1st to 10thDay
11%14%40%25%10%
420
11th to 20thDay
21%11%27%26%13%2
508
21st to endDay
16%10%28%28%16%2
600
May1st to 10thDay
14%8%28%33%15%3
603
11th to 20thDay
15%8%24%29%18%6%
625
21st to endDay
19%6%23%29%16%6%
679
June1st to 10thDay
17%8%28%28%13%5%
630
11th to 20thDay
21%8%28%26%13%3
630
21st to endDay
14%7%25%30%18%6%
630
July1st to 10thDay
9%324%32%25%7%
621
11th to 20thDay
12%6%26%28%23%5%
618
21st to endDay
7%6%26%31%22%8%
684
August1st to 10thDay
10%423%35%21%8%
626
11th to 20thDay
10%6%20%33%23%8%
615
21st to endDay
14%6%21%37%18%4
599
September1st to 10thDay
13%10%34%26%14%3
450
11th to 20thDay
19%8%26%30%13%4
378
21st to endDay
18%12%27%28%14%1
270
October1st to 10thDay
22%6%29%21%18%3
270
11th to 20thDay
13%13%33%24%11%6%
270
21st to endDay
14%11%37%26%8%4
297
November1st to 10thDay
27%5%29%25%10%4
270
11th to 20thDay
18%10%33%30%9%
270
21st to endDay
16%10%37%29%7%1
270
December1st to 10thDay
9%5%40%29%15%3
270
11th to 20thDay
14%7%46%24%7%1
270
21st to endDay
11%434%31%17%4
297
January1st to 10thNight
11%9%36%32%11%1
950
11th to 20thNight
16%9%32%32%9%1
905
21st to endNight
13%9%38%29%8%1
990
February1st to 10thNight
13%9%31%32%14%2
900
11th to 20thNight
11%7%34%35%11%2
766
21st to endNight
8%5%28%37%18%3
592
March1st to 10thNight
15%6%29%34%14%2
720
11th to 20thNight
11%6%34%33%15%1
689
21st to endNight
13%430%35%15%3
594
April1st to 10thNight
9%7%33%38%12%1
540
11th to 20thNight
17%6%32%33%11%
533
21st to endNight
20%6%32%32%9%1
540
May1st to 10thNight
15%6%26%37%14%2
540
11th to 20thNight
14%6%29%33%17%
531
21st to endNight
19%6%27%30%16%1
584
June1st to 10thNight
16%5%31%34%13%1
540
11th to 20thNight
21%430%32%13%1
384
21st to endNight
15%423%39%19%1
360
July1st to 10thNight
9%322%42%23%1
371
11th to 20thNight
9%429%37%20%2
522
21st to endNight
8%320%47%19%4
591
August1st to 10thNight
6%423%45%20%2
537
11th to 20thNight
10%418%40%25%4
534
21st to endNight
11%425%41%18%1
594
September1st to 10thNight
12%426%37%19%2
540
11th to 20thNight
15%5%26%40%13%1
540
21st to endNight
12%7%29%36%13%2
540
October1st to 10thNight
21%425%35%14%2
658
11th to 20thNight
13%7%30%36%13%1
847
21st to endNight
17%10%31%33%8%2
990
November1st to 10thNight
21%9%32%27%10%1
925
11th to 20thNight
15%9%37%27%10%2
950
21st to endNight
15%10%38%30%6%1
950
December1st to 10thNight
11%7%37%29%12%4
950
11th to 20thNight
12%11%34%31%11%1
950
21st to endNight
13%5%31%33%15%2
1045
Page generated at 2024-01-08 10:14:21. Version ac07

Copyright 2024 Attilla Danko


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