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 2017-04-07.

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
29%
14297
15%
45471
8%
14265
37%
14265
17%
31538

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
21%
686
17%
1716
5%
686
27%
686
19%
1259
April16th to endNight
33%
570
19%
1560
8%
570
40%
570
25%
1051
May1st to 15thNight
36%
371
18%
1361
13%
371
46%
371
20%
858
May16th to endNight
41%
342
16%
1369
13%
342
53%
342
22%
797
June1st to 15thNight
34%
330
11%
1320
9%
330
46%
330
16%
848
June16th to endNight
45%
330
10%
1320
12%
330
52%
330
23%
776
July1st to 15thNight
54%
310
17%
1240
22%
310
61%
310
31%
638
July16th to endNight
52%
353
15%
1311
12%
331
61%
331
29%
696
August1st to 15thNight
54%
494
17%
1474
11%
491
59%
491
34%
891
August16th to endNight
51%
611
21%
1661
9%
611
58%
611
36%
995
September1st to 15thNight
45%
660
20%
1650
9%
660
49%
660
31%
1096
September16th to endNight
48%
657
22%
1818
14%
657
53%
657
29%
1181
October1st to 15thNight
33%
660
18%
1980
11%
660
42%
660
20%
1380
October16th to endNight
20%
704
11%
2135
4%
704
30%
704
12%
1629
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%9%36%5%34446%33%
45767
Night
17%9%36%5%34446%34%
45642
Cloud CoverDay
17%9%36%5%3445%6%33%
45777
Night
17%9%36%5%34446%34%
45647
TransparencyDay
50%5%11%20%10%1
45456
Night
49%5%11%20%11%1
45471
SeeingDay
21%11%30%20%10%5%
4766
Night
22%12%29%23%10%1
14298

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
24%10%35%323335%33%
2048
16th to endDay
20%7%26%5%23345%38%
2079
May1st to 15thDay
16%6%35%5%36%5%47%35%
2260
16th to endDay
13%6%246%35%448%40%
2394
June1st to 15thDay
21%6%25%5%35%5%6%8%28%
2310
16th to endDay
15%5%36%5%35%5%5%9%34%
2310
July1st to 15thDay
12%3235%35%5%6%9%40%
2310
16th to endDay
10%6%26%6%46%5%6%9%34%
2451
August1st to 15thDay
12%6%26%5%45%6%6%8%36%
2145
16th to endDay
14%5%245%345%5%8%38%
2176
September1st to 15thDay
16%425%5%33446%41%
1980
16th to endDay
16%6%35%423446%42%
1810
October1st to 15thDay
21%6%25%6%25%35%6%32%
1650
16th to endDay
28%11%35%42445%425%
1735
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
21%8%44434445%34%
1716
16th to endNight
18%5%2442436%7%39%
1560
May1st to 15thNight
17%6%245%34448%39%
1361
16th to endNight
11%425%425%45%6%46%
1367
June1st to 15thNight
17%6%25%5%3445%8%35%
1320
16th to endNight
11%425%5%346%6%8%42%
1320
July1st to 15thNight
6%2145%25%45%8%53%
1320
16th to endNight
8%31432447%8%50%
1407
August1st to 15thNight
9%42443446%6%48%
1485
16th to endNight
8%5%2442345%8%50%
1661
September1st to 15thNight
14%5%2442445%7%44%
1650
16th to endNight
16%5%23324435%47%
1818
October1st to 15thNight
20%7%26%5%34336%36%
1980
16th to endNight
24%9%36%5%345%45%26%
2135
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
24%10%25%333345%33%
2048
16th to endDay
19%7%25%5%23236%38%
2079
May1st to 15thDay
15%7%35%5%35%5%5%7%35%
2260
16th to endDay
13%5%25%5%345%5%6%40%
2394
June1st to 15thDay
21%6%35%5%345%6%7%29%
2310
16th to endDay
15%6%36%5%25%5%7%8%34%
2310
July1st to 15thDay
12%424446%5%6%8%41%
2310
16th to endDay
9%7%25%6%45%7%6%9%34%
2451
August1st to 15thDay
11%6%25%5%36%6%6%8%36%
2145
16th to endDay
13%6%25%5%35%45%8%39%
2176
September1st to 15thDay
16%5%24434447%42%
1980
16th to endDay
15%7%25%423445%43%
1810
October1st to 15thDay
19%7%36%6%34446%33%
1650
16th to endDay
27%11%46%424445%25%
1735
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
21%8%45%42445%6%33%
1716
16th to endNight
18%6%244235%5%6%40%
1560
May1st to 15thNight
17%6%245%24347%40%
1361
16th to endNight
11%5%24435%45%7%45%
1367
June1st to 15thNight
17%6%25%5%3445%8%35%
1320
16th to endNight
11%426%5%245%6%9%42%
1320
July1st to 15thNight
6%3145%245%5%7%53%
1320
16th to endNight
7%313415%5%7%8%50%
1407
August1st to 15thNight
9%5%2442445%8%48%
1485
16th to endNight
8%5%25%32435%8%50%
1661
September1st to 15thNight
14%6%1442346%7%44%
1650
16th to endNight
16%5%14324445%47%
1818
October1st to 15thNight
19%8%35%5%34346%36%
1980
16th to endNight
24%9%27%6%25%45%5%26%
2135
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
54%38%17%13%2
2048
16th to endDay
47%27%21%18%2
2079
May1st to 15thDay
46%6%9%20%15%2
2260
16th to endDay
42%6%12%22%14%1
2398
June1st to 15thDay
51%7%12%18%10%
2310
16th to endDay
45%7%12%21%12%1
2310
July1st to 15thDay
35%7%12%29%14%
2161
16th to endDay
42%9%13%23%9%1
2284
August1st to 15thDay
42%7%15%21%12%1
2132
16th to endDay
41%6%12%27%10%1
2176
September1st to 15thDay
40%6%13%26%12%
1980
16th to endDay
41%6%10%30%10%
1810
October1st to 15thDay
50%5%11%20%10%1
1650
16th to endDay
60%412%14%7%
1735
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
51%47%18%15%2
1716
16th to endNight
41%6%9%20%18%3
1560
May1st to 15thNight
43%5%10%21%15%3
1361
16th to endNight
37%6%12%23%17%3
1369
June1st to 15thNight
47%5%12%19%15%
1320
16th to endNight
38%6%15%22%15%1
1320
July1st to 15thNight
27%7%11%31%21%1
1240
16th to endNight
29%7%15%29%15%1
1311
August1st to 15thNight
33%5%17%27%14%
1474
16th to endNight
31%6%12%33%15%1
1661
September1st to 15thNight
38%6%13%28%12%
1650
16th to endNight
38%5%10%30%14%
1818
October1st to 15thNight
48%5%9%22%12%
1980
16th to endNight
57%6%11%15%8%
2135
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
32%14%28%12%9%1
235
16th to endDay
20%15%30%16%10%6%
210
May1st to 15thDay
23%10%29%20%7%8%
228
16th to endDay
13%14%35%20%10%5%
267
June1st to 15thDay
23%10%30%22%9%2
255
16th to endDay
16%6%32%24%14%3
255
July1st to 15thDay
14%428%29%14%7%
245
16th to endDay
11%6%37%24%11%8%
270
August1st to 15thDay
10%5%28%28%16%9%
253
16th to endDay
17%424%22%17%13%
268
September1st to 15thDay
16%7%25%20%15%14%
255
16th to endDay
18%9%23%28%9%10%
254
October1st to 15thDay
22%11%27%21%12%4
255
16th to endDay
33%14%29%18%3
267
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
27%15%29%21%5%
686
16th to endNight
21%13%28%23%12%1
570
May1st to 15thNight
20%7%30%26%13%1
371
16th to endNight
13%6%34%30%13%
343
June1st to 15thNight
19%8%29%30%11%1
330
16th to endNight
13%6%27%39%13%1
330
July1st to 15thNight
6%326%42%19%
310
16th to endNight
7%232%36%20%
353
August1st to 15thNight
12%223%34%23%3
494
16th to endNight
10%327%30%25%2
611
September1st to 15thNight
16%5%27%25%22%2
660
16th to endNight
18%7%21%24%24%3
657
October1st to 15thNight
23%9%28%23%14%1
660
16th to endNight
30%14%27%21%5%
704
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 2017-04-08 05:35:15. Version ac04

Copyright 2017 A. Danko


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