Marmora
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marmora clear sky chart from 2005-11-05 to 2017-10-31.

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
30%
14911
15%
47393
8%
14879
38%
14879
18%
32707

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
10%
2506
3%
716
22%
716
7%
1962
January16th to endNight
18%
768
12%
2553
5%
768
27%
768
10%
1948
February1st to 15thNight
14%
704
11%
2287
3%
701
24%
701
10%
1732
February16th to endNight
20%
631
15%
1994
5%
631
32%
631
13%
1441
March1st to 15thNight
19%
720
15%
2027
6%
720
28%
720
16%
1472
March16th to endNight
27%
768
21%
2085
9%
768
37%
768
23%
1408
April1st to 15thNight
22%
718
16%
1796
5%
718
28%
718
19%
1307
April16th to endNight
31%
622
19%
1702
8%
622
39%
622
24%
1141
May1st to 15thNight
36%
405
17%
1485
12%
405
45%
405
19%
962
May16th to endNight
40%
374
16%
1497
12%
374
52%
374
21%
888
June1st to 15thNight
36%
360
11%
1440
8%
360
47%
360
17%
913
June16th to endNight
44%
360
11%
1440
12%
360
50%
360
22%
862
July1st to 15thNight
53%
340
16%
1360
20%
340
60%
340
31%
709
July16th to endNight
53%
382
16%
1424
15%
360
62%
360
29%
760
August1st to 15thNight
56%
539
16%
1609
10%
536
60%
536
34%
976
August16th to endNight
52%
667
23%
1813
10%
667
59%
667
37%
1072
September1st to 15thNight
46%
720
19%
1800
9%
720
51%
720
32%
1175
September16th to endNight
50%
717
24%
1984
17%
717
55%
717
30%
1266
October1st to 15thNight
34%
720
17%
2160
11%
720
42%
720
21%
1489
October16th to endNight
20%
768
13%
2327
5%
768
31%
768
13%
1744
November1st to 15thNight
30%
700
19%
2376
14%
700
39%
700
18%
1576
November16th to endNight
21%
720
12%
2520
7%
720
29%
720
11%
1864
December1st to 15thNight
16%
720
8%
2520
3%
720
22%
720
9%
1928
December16th to endNight
11%
768
9%
2688
1%
768
20%
768
8%
2112

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%8%36%5%34446%33%
48361
Night
17%8%36%5%34446%35%
47564
Cloud CoverDay
17%9%36%5%3445%6%33%
48371
Night
16%8%36%5%34446%35%
47569
TransparencyDay
50%5%11%20%10%1
48050
Night
48%5%11%20%11%1
47393
SeeingDay
21%12%29%20%10%5%
5587
Night
22%12%29%23%10%1
14912

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
20%16%5%6%5%2344426%
1432
16th to endDay
14%15%6%10%8%35%34323%
1668
February1st to 15thDay
14%14%6%11%8%34445%22%
1575
16th to endDay
17%15%38%7%3343428%
1479
March1st to 15thDay
17%12%48%5%36%346%28%
1921
16th to endDay
16%8%35%5%23345%40%
2139
April1st to 15thDay
23%10%35%323335%33%
2152
16th to endDay
20%7%25%5%23346%38%
2268
May1st to 15thDay
18%7%35%5%35%447%33%
2466
16th to endDay
14%6%25%6%35%448%38%
2618
June1st to 15thDay
21%6%25%5%35%5%5%8%30%
2520
16th to endDay
16%6%35%5%35%5%5%8%33%
2520
July1st to 15thDay
13%4235%45%5%6%8%40%
2520
16th to endDay
10%6%26%7%46%5%6%9%34%
2646
August1st to 15thDay
12%5%26%5%45%6%6%8%35%
2340
16th to endDay
13%5%245%445%5%8%39%
2375
September1st to 15thDay
15%4245%33446%43%
2160
16th to endDay
15%5%34423446%44%
1974
October1st to 15thDay
22%6%25%6%25%346%32%
1800
16th to endDay
27%10%35%5%2445%425%
1893
November1st to 15thDay
16%7%38%4345%5%6%35%
1479
16th to endDay
22%13%46%6%24445%24%
1440
December1st to 15thDay
18%18%48%5%445%4420%
1440
16th to endDay
22%16%6%8%6%2434321%
1536
January1st to 15thNight
21%14%5%9%6%34335%22%
2506
16th to endNight
14%14%5%8%6%35%5%45%25%
2553
February1st to 15thNight
14%14%6%7%7%35%446%25%
2285
16th to endNight
16%11%47%5%345%5%430%
1994
March1st to 15thNight
19%9%36%5%34435%32%
2015
16th to endNight
15%7%36%423445%42%
2085
April1st to 15thNight
20%8%45%434445%35%
1796
16th to endNight
17%5%2442436%7%40%
1702
May1st to 15thNight
19%6%245%34447%38%
1485
16th to endNight
12%5%25%425%45%6%44%
1495
June1st to 15thNight
16%6%25%5%3445%7%37%
1440
16th to endNight
12%435%4346%6%8%41%
1440
July1st to 15thNight
7%31442445%8%52%
1440
16th to endNight
9%31432446%8%49%
1520
August1st to 15thNight
9%42443446%7%47%
1620
16th to endNight
8%42442345%9%50%
1813
September1st to 15thNight
14%5%2442345%7%46%
1800
16th to endNight
15%5%13323435%48%
1984
October1st to 15thNight
20%7%25%5%24346%37%
2160
16th to endNight
23%8%36%5%34445%28%
2327
November1st to 15thNight
18%7%345%34347%36%
2376
16th to endNight
23%9%36%5%36%45%5%26%
2520
December1st to 15thNight
22%15%45%5%24446%23%
2520
16th to endNight
22%15%6%7%5%34445%20%
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
20%16%47%42344426%
1432
16th to endDay
13%15%6%10%7%35%44423%
1668
February1st to 15thDay
14%13%6%11%8%35%435%22%
1575
16th to endDay
17%14%5%6%7%33345%27%
1479
March1st to 15thDay
17%11%39%5%34446%28%
1932
16th to endDay
16%8%35%5%33345%40%
2138
April1st to 15thDay
23%10%25%323345%33%
2152
16th to endDay
20%7%25%5%23236%38%
2268
May1st to 15thDay
17%7%35%5%35%5%46%34%
2466
16th to endDay
14%5%35%5%345%5%6%39%
2618
June1st to 15thDay
20%6%35%5%445%6%7%30%
2520
16th to endDay
15%6%36%5%25%5%6%8%34%
2520
July1st to 15thDay
12%424446%5%6%8%40%
2520
16th to endDay
9%6%25%7%46%7%6%9%34%
2646
August1st to 15thDay
11%6%25%5%46%5%6%8%36%
2340
16th to endDay
13%6%25%5%35%45%8%39%
2375
September1st to 15thDay
15%5%24434447%43%
2160
16th to endDay
14%6%25%434445%45%
1974
October1st to 15thDay
20%7%36%6%24446%33%
1800
16th to endDay
26%10%46%5%24445%26%
1893
November1st to 15thDay
16%7%36%5%3346%5%35%
1479
16th to endDay
22%12%46%6%2435%5%24%
1440
December1st to 15thDay
19%17%5%8%5%4445%421%
1440
16th to endDay
21%15%6%8%6%2442421%
1536
January1st to 15thNight
21%14%5%8%6%3433422%
2506
16th to endNight
15%14%5%9%6%34445%25%
2553
February1st to 15thNight
14%13%5%8%7%35%5%46%25%
2278
16th to endNight
16%10%47%6%35%45%5%30%
1994
March1st to 15thNight
19%10%36%5%44445%31%
2027
16th to endNight
15%7%35%5%24445%42%
2085
April1st to 15thNight
20%8%35%424446%34%
1796
16th to endNight
17%5%244235%5%7%40%
1702
May1st to 15thNight
18%6%245%24447%38%
1485
16th to endNight
11%5%25%436%45%7%43%
1495
June1st to 15thNight
16%6%25%5%34448%37%
1440
16th to endNight
12%426%5%245%6%8%40%
1440
July1st to 15thNight
6%3145%245%5%8%52%
1440
16th to endNight
8%414425%47%8%50%
1520
August1st to 15thNight
8%5%2442445%9%47%
1620
16th to endNight
7%425%32335%9%51%
1813
September1st to 15thNight
14%5%1442335%7%46%
1800
16th to endNight
15%5%14324446%48%
1984
October1st to 15thNight
19%7%35%5%34346%37%
2160
16th to endNight
23%9%26%6%35%445%28%
2327
November1st to 15thNight
18%7%25%5%24347%36%
2376
16th to endNight
23%9%35%6%35%446%27%
2520
December1st to 15thNight
21%14%46%43445%6%23%
2520
16th to endNight
22%14%5%8%6%24445%20%
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
60%410%17%6%
1433
16th to endDay
63%49%13%8%1
1668
February1st to 15thDay
63%5%10%15%4
1577
16th to endDay
59%48%14%11%1
1479
March1st to 15thDay
56%5%13%16%6%1
1932
16th to endDay
46%47%21%15%3
2139
April1st to 15thDay
53%38%18%13%2
2152
16th to endDay
47%38%22%16%2
2268
May1st to 15thDay
49%6%9%19%13%2
2466
16th to endDay
43%6%12%21%14%1
2622
June1st to 15thDay
50%7%11%19%10%
2520
16th to endDay
45%7%12%21%12%1
2520
July1st to 15thDay
36%7%12%28%13%
2371
16th to endDay
43%8%13%23%8%1
2479
August1st to 15thDay
42%7%15%21%11%1
2327
16th to endDay
41%6%13%27%11%
2375
September1st to 15thDay
39%6%13%26%13%
2160
16th to endDay
39%6%10%31%10%
1974
October1st to 15thDay
51%5%10%21%10%
1800
16th to endDay
59%5%12%15%7%
1893
November1st to 15thDay
48%6%14%18%11%1
1479
16th to endDay
60%5%12%13%7%
1440
December1st to 15thDay
64%5%13%12%3
1440
16th to endDay
67%5%8%13%6%
1536
January1st to 15thNight
65%49%13%6%
2506
16th to endNight
59%6%8%16%9%
2553
February1st to 15thNight
59%5%12%16%5%
2287
16th to endNight
54%5%10%20%9%
1994
March1st to 15thNight
53%411%20%8%
2027
16th to endNight
43%49%22%17%2
2085
April1st to 15thNight
50%48%19%15%2
1796
16th to endNight
40%6%10%20%18%2
1702
May1st to 15thNight
45%5%9%20%15%3
1485
16th to endNight
39%6%12%23%15%2
1497
June1st to 15thNight
45%5%12%20%16%
1440
16th to endNight
39%6%15%22%15%1
1440
July1st to 15thNight
27%7%11%30%21%1
1360
16th to endNight
30%6%14%30%16%1
1424
August1st to 15thNight
32%6%18%27%13%
1609
16th to endNight
30%6%13%33%15%
1813
September1st to 15thNight
36%6%14%27%13%1
1800
16th to endNight
37%5%10%31%14%
1984
October1st to 15thNight
47%5%9%23%13%
2160
16th to endNight
56%6%12%17%7%
2327
November1st to 15thNight
47%5%13%20%12%1
2376
16th to endNight
56%6%12%17%5%
2520
December1st to 15thNight
60%6%14%14%4
2520
16th to endNight
64%5%10%12%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
23%30%30%13%11
60
16th to endDay
38%13%30%15%2
86
February1st to 15thDay
30%32%34%3
90
16th to endDay
36%18%31%10%2
138
March1st to 15thDay
25%14%33%18%6%
270
16th to endDay
26%16%32%14%7%1
288
April1st to 15thDay
30%15%30%12%8%1
270
16th to endDay
23%20%27%15%8%4
270
May1st to 15thDay
29%10%26%19%6%6%
288
16th to endDay
17%14%36%17%9%4
331
June1st to 15thDay
23%10%31%22%9%2
315
16th to endDay
19%9%33%22%12%3
315
July1st to 15thDay
15%6%28%27%15%6%
305
16th to endDay
11%7%35%23%13%7%
326
August1st to 15thDay
10%5%28%29%16%9%
313
16th to endDay
16%5%25%22%17%12%
332
September1st to 15thDay
13%8%26%21%15%14%
315
16th to endDay
15%9%20%27%14%12%
314
October1st to 15thDay
24%11%27%19%11%5%
315
16th to endDay
30%17%28%19%3
329
November1st to 15thDay
24%7%33%22%10%2
133
16th to endDay
28%15%28%20%6%1
60
December1st to 15thDay
25%21%31%18%3
60
16th to endDay
34%29%32%3
64
January1st to 15thNight
30%18%29%16%4
720
16th to endNight
24%15%33%21%4
768
February1st to 15thNight
22%20%36%17%3
704
16th to endNight
22%18%34%19%5%
631
March1st to 15thNight
26%15%33%20%3
720
16th to endNight
20%15%31%21%9%1
768
April1st to 15thNight
26%16%29%22%5%
718
16th to endNight
20%14%30%22%11%1
622
May1st to 15thNight
22%7%28%26%12%1
405
16th to endNight
13%6%34%29%13%
375
June1st to 15thNight
18%7%29%30%12%1
360
16th to endNight
14%6%27%37%12%1
360
July1st to 15thNight
7%327%41%18%
340
16th to endNight
8%230%37%20%
382
August1st to 15thNight
11%222%36%23%3
539
16th to endNight
9%427%30%25%2
667
September1st to 15thNight
15%5%26%26%22%3
720
16th to endNight
17%7%20%24%25%4
717
October1st to 15thNight
22%9%27%23%14%2
720
16th to endNight
29%15%27%21%5%
768
November1st to 15thNight
23%10%30%23%10%1
700
16th to endNight
28%16%26%19%8%
720
December1st to 15thNight
30%19%29%17%3
720
16th to endNight
31%15%34%14%2
768
Page generated at 2017-11-01 17:23:38. Version ac04

Copyright 2017 A. Danko


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