Tobermory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tobermory clear sky chart from 2005-11-06 to 2024-02-20.

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
32%
23644
10%
80919
8%
23552
36%
23552
12%
62647

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
10%
942
1%
4732
1%
926
11%
926
2%
4366
January11th to 20thNight
10%
945
2%
4438
1%
930
11%
930
2%
4188
January21st to endNight
19%
873
3%
4602
3%
863
21%
863
3%
4038
February1st to 10thNight
16%
760
7%
2470
3%
760
20%
760
7%
2059
February11th to 20thNight
22%
740
9%
2399
4%
739
28%
739
10%
1926
February21st to endNight
21%
592
10%
1794
3%
592
28%
592
11%
1409
March1st to 10thNight
29%
720
14%
2068
8%
720
34%
720
19%
1488
March11th to 20thNight
28%
720
17%
1980
8%
720
35%
720
20%
1449
March21st to endNight
37%
792
17%
2178
9%
792
43%
792
22%
1536
April1st to 10thNight
32%
689
14%
1877
6%
689
37%
689
20%
1350
April11th to 20thNight
42%
533
21%
1597
12%
533
47%
533
24%
1057
April21st to endNight
39%
540
16%
1620
10%
540
43%
540
19%
1162
May1st to 10thNight
49%
540
14%
1620
12%
540
52%
540
23%
1094
May11th to 20thNight
51%
442
18%
1504
20%
442
54%
442
22%
941
May21st to endNight
58%
389
15%
1511
19%
388
62%
388
23%
877
June1st to 10thNight
53%
360
14%
1260
16%
360
59%
360
22%
784
June11th to 20thNight
61%
360
16%
1260
18%
360
65%
360
28%
741
June21st to endNight
60%
360
13%
1260
15%
360
63%
360
25%
784
July1st to 10thNight
70%
350
19%
1225
23%
350
72%
350
35%
640
July11th to 20thNight
64%
392
18%
1262
21%
392
66%
392
31%
749
July21st to endNight
67%
591
16%
1606
16%
558
67%
558
34%
965
August1st to 10thNight
63%
537
17%
1600
16%
534
65%
534
33%
938
August11th to 20thNight
64%
534
18%
1598
15%
534
67%
534
31%
963
August21st to endNight
54%
594
18%
1782
12%
594
57%
594
27%
1145
September1st to 10thNight
57%
688
18%
1812
11%
688
59%
688
31%
1164
September11th to 20thNight
55%
720
20%
1980
14%
720
57%
720
31%
1298
September21st to endNight
46%
720
18%
1980
13%
720
48%
720
23%
1385
October1st to 10thNight
38%
720
14%
2116
12%
720
42%
720
18%
1557
October11th to 20thNight
28%
720
8%
2160
6%
720
31%
720
11%
1746
October21st to endNight
21%
792
9%
2484
6%
792
25%
792
8%
2073
November1st to 10thNight
26%
740
13%
2435
11%
740
31%
740
12%
1885
November11th to 20thNight
15%
760
6%
2660
6%
760
17%
760
7%
2226
November21st to endNight
13%
760
4%
2660
3%
760
14%
760
4%
2353
December1st to 10thNight
8%
760
2%
2660
1%
760
10%
760
2%
2440
December11th to 20thNight
7%
931
2%
3497
0%
930
8%
930
3%
3091
December21st to endNight
6%
1038
1%
5232
0%
1026
7%
1026
1%
4780

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
15%11%48%6%3445%6%32%
78078
Night
17%14%6%10%7%34445%25%
81123
TransparencyDay
51%7%12%19%10%1
77782
Night
60%7%10%14%8%1
80954
SeeingDay
18%6%22%30%19%4
14216
Night
22%9%26%26%14%3
23678

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%25%13%14%9%334228%
2220
11th to 20thDay
13%21%10%23%14%5%5%3223
2530
21st to endDay
20%20%8%14%9%45%5%448%
3036
February1st to 10thDay
14%18%7%14%12%46%345%14%
1710
11th to 20thDay
13%14%8%12%9%6%6%5%5%5%19%
1654
21st to endDay
14%15%7%10%7%46%5%5%5%22%
1458
March1st to 10thDay
13%9%38%7%45%45%7%35%
1888
11th to 20thDay
12%9%5%10%6%35%45%7%34%
1980
21st to endDay
16%8%37%6%35%45%5%38%
2178
April1st to 10thDay
19%9%47%5%3445%6%33%
2097
11th to 20thDay
18%7%35%5%34447%40%
2312
21st to endDay
18%8%45%43445%7%38%
2340
May1st to 10thDay
18%7%245%345%5%6%40%
2340
11th to 20thDay
15%7%35%5%34447%44%
2388
21st to endDay
11%5%26%43446%9%46%
2762
June1st to 10thDay
13%5%26%435%5%6%7%42%
2700
11th to 20thDay
11%6%35%5%345%6%9%43%
2700
21st to endDay
12%6%35%5%35%5%6%8%41%
2700
July1st to 10thDay
7%4244345%6%8%52%
2700
11th to 20thDay
9%5%25%5%35%5%6%8%47%
2652
21st to endDay
9%5%24435%5%6%9%49%
2615
August1st to 10thDay
12%5%243245%7%8%49%
2327
11th to 20thDay
9%5%25%4345%7%8%49%
2303
21st to endDay
11%7%25%6%345%6%8%44%
2574
September1st to 10thDay
13%5%35%5%45%5%5%7%43%
2126
11th to 20thDay
13%5%25%425%46%8%46%
1980
21st to endDay
18%6%36%5%45%45%7%37%
1980
October1st to 10thDay
19%9%36%5%45%45%8%32%
1842
11th to 20thDay
27%11%47%6%35%45%6%23%
1800
21st to endDay
27%15%5%8%5%3445%5%19%
1868
November1st to 10thDay
19%16%5%8%5%35%5%5%6%22%
1641
11th to 20thDay
19%19%6%10%6%35%5%5%7%16%
1520
21st to endDay
25%20%7%11%7%3344410%
1520
December1st to 10thDay
18%27%10%14%9%333337%
1520
11th to 20thDay
20%22%9%15%8%343448%
1686
21st to endDay
27%23%8%16%6%343334
2431
January1st to 10thNight
16%27%11%17%10%323226%
4734
11th to 20thNight
15%17%12%23%14%333225%
4440
21st to endNight
16%18%9%15%10%45%44410%
4620
February1st to 10thNight
13%18%8%15%11%5%3445%15%
2470
11th to 20thNight
13%16%8%12%9%45%5%4420%
2397
21st to endNight
16%14%7%9%8%45%45%5%22%
1794
March1st to 10thNight
14%10%5%8%7%4445%5%33%
2058
11th to 20thNight
14%11%5%8%6%345%5%6%33%
1979
21st to endNight
16%8%47%6%34447%36%
2178
April1st to 10thNight
21%10%46%43446%6%32%
1877
11th to 20thNight
17%7%35%4345%6%7%38%
1597
21st to endNight
20%9%37%5%45%445%34%
1620
May1st to 10thNight
13%8%38%5%5%6%5%5%6%37%
1620
11th to 20thNight
14%7%35%5%45%45%5%42%
1503
21st to endNight
11%6%36%435%45%8%45%
1510
June1st to 10thNight
12%7%35%7%345%5%8%40%
1260
11th to 20thNight
9%5%35%5%35%5%6%9%44%
1260
21st to endNight
10%7%25%45%5%5%6%8%41%
1260
July1st to 10thNight
7%415%42445%9%55%
1260
11th to 20thNight
8%6%25%6%35%5%6%10%45%
1304
21st to endNight
8%5%24435%5%5%8%51%
1701
August1st to 10thNight
9%5%25%43447%7%51%
1611
11th to 20thNight
9%5%25%435%5%6%8%48%
1598
21st to endNight
12%6%36%5%35%5%6%7%43%
1782
September1st to 10thNight
12%5%35%5%35%45%8%46%
1812
11th to 20thNight
13%5%25%4345%6%7%45%
1980
21st to endNight
19%7%35%6%3445%6%38%
1980
October1st to 10thNight
22%9%37%6%4435%5%32%
2116
11th to 20thNight
26%11%48%6%35%446%22%
2160
21st to endNight
28%16%5%7%6%44345%18%
2484
November1st to 10thNight
21%16%47%7%34446%24%
2435
11th to 20thNight
19%22%7%10%7%35%43416%
2660
21st to endNight
25%23%7%10%7%3434411%
2660
December1st to 10thNight
23%26%11%14%6%333228%
2660
11th to 20thNight
19%23%8%14%8%3344411%
3507
21st to endNight
25%22%10%14%7%343336%
5236

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
81%8%7%4
2221
11th to 20thDay
89%4331
2530
21st to endDay
76%10%8%5%2
3036
February1st to 10thDay
71%6%9%11%2
1710
11th to 20thDay
65%7%10%12%6%
1663
21st to endDay
61%7%11%17%4
1458
March1st to 10thDay
47%9%15%17%11%2
1891
11th to 20thDay
50%7%11%21%9%3
1980
21st to endDay
48%5%11%20%13%3
2178
April1st to 10thDay
51%6%13%19%11%1
2097
11th to 20thDay
45%5%8%26%14%2
2312
21st to endDay
45%6%13%20%13%3
2340
May1st to 10thDay
42%6%10%24%14%3
2340
11th to 20thDay
41%6%9%24%18%2
2392
21st to endDay
35%8%16%23%16%2
2762
June1st to 10thDay
39%7%12%26%15%1
2700
11th to 20thDay
36%7%11%28%17%1
2700
21st to endDay
38%9%13%25%13%2
2700
July1st to 10thDay
28%7%17%28%18%2
2626
11th to 20thDay
33%9%15%29%12%2
2571
21st to endDay
31%9%14%29%15%1
2470
August1st to 10thDay
32%8%18%29%14%1
2314
11th to 20thDay
31%8%19%29%12%
2303
21st to endDay
38%8%15%25%12%1
2574
September1st to 10thDay
38%8%13%27%12%1
2126
11th to 20thDay
35%8%16%31%10%
1980
21st to endDay
46%7%15%24%7%
1980
October1st to 10thDay
51%6%12%18%12%1
1842
11th to 20thDay
62%7%14%12%5%
1800
21st to endDay
66%7%10%12%4
1868
November1st to 10thDay
61%8%12%14%5%
1641
11th to 20thDay
68%8%10%10%4
1520
21st to endDay
76%7%9%5%2
1520
December1st to 10thDay
82%6%7%42
1520
11th to 20thDay
79%8%7%7%
1686
21st to endDay
85%7%5%2
2431
January1st to 10thNight
82%8%6%31
4734
11th to 20thNight
86%6%431
4440
21st to endNight
76%8%7%6%2
4620
February1st to 10thNight
71%6%9%11%3
2470
11th to 20thNight
65%7%9%14%5%
2399
21st to endNight
61%7%11%13%7%
1794
March1st to 10thNight
49%8%13%18%11%1
2068
11th to 20thNight
51%7%10%19%12%2
1980
21st to endNight
48%6%9%20%15%3
2178
April1st to 10thNight
51%5%10%21%12%2
1877
11th to 20thNight
44%6%8%23%17%2
1597
21st to endNight
52%5%9%16%15%3
1620
May1st to 10thNight
46%6%11%21%14%3
1620
11th to 20thNight
43%6%7%23%19%3
1504
21st to endNight
38%6%14%23%15%4
1511
June1st to 10thNight
41%7%9%22%18%2
1260
11th to 20thNight
35%7%13%23%20%2
1260
21st to endNight
39%7%14%24%14%2
1260
July1st to 10thNight
27%6%12%29%21%4
1225
11th to 20thNight
33%8%13%27%18%1
1262
21st to endNight
32%7%15%27%18%1
1606
August1st to 10thNight
30%9%17%28%15%2
1600
11th to 20thNight
33%8%17%27%14%1
1598
21st to endNight
39%7%15%24%12%2
1782
September1st to 10thNight
36%8%12%27%15%2
1812
11th to 20thNight
37%8%14%30%10%
1980
21st to endNight
46%7%14%24%8%
1980
October1st to 10thNight
54%6%9%20%11%
2116
11th to 20thNight
62%8%11%14%4
2160
21st to endNight
68%8%8%11%5%
2484
November1st to 10thNight
60%7%11%17%5%
2435
11th to 20thNight
69%8%11%8%31
2660
21st to endNight
76%9%9%5%1
2660
December1st to 10thNight
83%6%6%41
2660
11th to 20thNight
77%7%9%5%1
3506
21st to endNight
82%7%8%2
5236

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
23%13%34%20%9%
186
11th to 20thDay
21%9%38%22%10%
270
21st to endDay
29%7%22%32%9%1
297
February1st to 10thDay
21%12%35%24%8%
270
11th to 20thDay
18%11%37%31%3
267
21st to endDay
21%17%37%23%2
198
March1st to 10thDay
18%10%33%29%10%1
331
11th to 20thDay
17%12%27%33%11%1
420
21st to endDay
24%5%26%33%10%2
462
April1st to 10thDay
20%7%26%33%10%2
420
11th to 20thDay
22%7%24%28%13%6%
412
21st to endDay
22%7%24%33%13%1
420
May1st to 10thDay
22%319%37%18%2
423
11th to 20thDay
17%316%34%24%6%
447
21st to endDay
13%216%35%26%8%
522
June1st to 10thDay
12%118%39%25%4
630
11th to 20thDay
13%317%36%27%5%
630
21st to endDay
14%215%37%27%4
630
July1st to 10thDay
8%111%42%31%6%
621
11th to 20thDay
11%215%33%31%8%
618
21st to endDay
12%214%37%31%5%
556
August1st to 10thDay
15%313%26%33%9%
446
11th to 20thDay
10%210%29%38%11%
439
21st to endDay
14%417%32%26%8%
495
September1st to 10thDay
14%419%26%28%9%
450
11th to 20thDay
11%417%29%29%10%
450
21st to endDay
18%7%18%26%23%8%
450
October1st to 10thDay
22%8%22%24%18%5%
450
11th to 20thDay
27%13%24%28%7%1
450
21st to endDay
30%13%28%21%6%1
383
November1st to 10thDay
22%12%32%24%9%1
255
11th to 20thDay
28%13%34%21%5%
180
21st to endDay
27%14%36%21%2
180
December1st to 10thDay
26%19%29%21%41
180
11th to 20thDay
28%21%32%16%4
180
21st to endDay
33%16%35%13%31
198
January1st to 10thNight
25%17%30%22%6%1
950
11th to 20thNight
25%15%29%23%7%1
950
21st to endNight
21%9%34%26%9%2
885
February1st to 10thNight
20%13%37%24%6%1
760
11th to 20thNight
19%11%35%26%9%
742
21st to endNight
23%11%34%26%6%1
592
March1st to 10thNight
18%8%34%30%8%1
720
11th to 20thNight
19%8%36%25%10%2
720
21st to endNight
19%5%30%31%14%1
792
April1st to 10thNight
25%8%29%30%8%1
689
11th to 20thNight
21%8%23%30%14%4
533
21st to endNight
25%5%22%30%15%2
540
May1st to 10thNight
17%221%38%20%3
540
11th to 20thNight
17%416%36%24%3
442
21st to endNight
15%216%40%21%6%
389
June1st to 10thNight
15%417%39%23%3
360
11th to 20thNight
12%316%41%24%5%
360
21st to endNight
12%313%38%30%4
360
July1st to 10thNight
8%212%45%28%5%
350
11th to 20thNight
10%216%33%31%9%
392
21st to endNight
9%213%40%32%4
591
August1st to 10thNight
10%214%34%33%7%
537
11th to 20thNight
12%214%29%34%10%
534
21st to endNight
13%418%31%26%7%
594
September1st to 10thNight
13%320%30%24%10%
688
11th to 20thNight
15%5%19%28%24%9%
720
21st to endNight
21%6%19%23%23%8%
720
October1st to 10thNight
25%6%23%24%19%3
720
11th to 20thNight
29%12%25%22%10%2
720
21st to endNight
34%10%28%22%5%1
792
November1st to 10thNight
28%13%27%21%9%1
740
11th to 20thNight
28%17%31%16%8%
760
21st to endNight
33%15%29%17%5%1
760
December1st to 10thNight
33%18%30%13%6%
760
11th to 20thNight
28%19%34%13%5%1
931
21st to endNight
32%16%32%15%4
1045
Page generated at 2024-02-17 06:28:41. Version ac07

Copyright 2024 Attilla Danko


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