Scenic
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Scenic clear sky chart from 2005-11-05 to 2018-01-20.

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
47%
16675
21%
48467
13%
16634
54%
16634
33%
29202

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
43%
974
18%
2716
12%
970
48%
970
30%
1749
January16th to endNight
38%
985
21%
2758
11%
985
47%
985
31%
1715
February1st to 15thNight
39%
739
15%
2259
10%
739
46%
739
26%
1456
February16th to endNight
40%
632
20%
1894
12%
632
47%
632
30%
1176
March1st to 15thNight
46%
720
19%
2160
12%
720
52%
720
31%
1306
March16th to endNight
42%
606
18%
2019
12%
606
50%
606
25%
1265
April1st to 15thNight
38%
539
17%
1798
13%
539
46%
539
24%
1126
April16th to endNight
40%
540
15%
1689
12%
540
46%
540
22%
1134
May1st to 15thNight
46%
540
18%
1566
13%
540
51%
540
30%
989
May16th to endNight
41%
562
16%
1498
8%
561
44%
561
29%
1014
June1st to 15thNight
47%
540
13%
1440
6%
540
49%
540
32%
936
June16th to endNight
53%
540
17%
1440
7%
540
57%
540
46%
808
July1st to 15thNight
65%
510
16%
1360
9%
510
68%
510
49%
748
July16th to endNight
69%
564
24%
1416
16%
531
70%
531
53%
742
August1st to 15thNight
63%
539
23%
1505
17%
536
68%
536
42%
850
August16th to endNight
65%
573
29%
1895
28%
573
73%
573
46%
912
September1st to 15thNight
57%
540
25%
1815
22%
540
67%
540
41%
913
September16th to endNight
58%
537
31%
1980
29%
537
68%
537
42%
924
October1st to 15thNight
45%
624
26%
2064
18%
624
53%
624
28%
1227
October16th to endNight
50%
931
26%
2467
12%
931
56%
931
37%
1497
November1st to 15thNight
46%
950
26%
2470
14%
950
52%
950
38%
1512
November16th to endNight
47%
975
28%
2616
16%
975
55%
975
37%
1575
December1st to 15thNight
40%
975
17%
2730
9%
975
47%
975
30%
1758
December16th to endNight
43%
1040
20%
2912
12%
1040
51%
1040
29%
1870

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
8%42442445%7%50%
49065
Night
8%5%2442445%7%49%
48634
Cloud CoverDay
8%5%2442445%8%50%
49075
Night
8%5%2442445%7%49%
48639
Cloud CoverDay
8%5%2442445%7%50%
49073
Night
8%5%2442445%7%49%
48639
TransparencyDay
31%6%15%26%15%4
48749
Night
32%6%15%25%16%3
48467
SeeingDay
10%5%26%33%19%3
6436
Night
10%5%30%40%12%
16681

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
5%5%38%6%2445%7%44%
1552
16th to endDay
5%7%344245%5%8%48%
1570
February1st to 15thDay
7%9%46%6%24446%42%
1610
16th to endDay
5%7%35%6%35%5%6%7%45%
1580
March1st to 15thDay
6%5%35%4235%47%52%
1790
16th to endDay
11%6%25%4345%7%8%41%
2202
April1st to 15thDay
12%6%3442345%8%43%
2150
16th to endDay
17%6%2442445%8%38%
2269
May1st to 15thDay
13%6%2442345%6%46%
2384
16th to endDay
16%6%244245%6%8%39%
2616
June1st to 15thDay
11%31332446%9%47%
2520
16th to endDay
31232346%8%62%
2520
July1st to 15thDay
6%21332347%8%56%
2520
16th to endDay
5%21241445%7%60%
2656
August1st to 15thDay
5%3134245%6%9%51%
2445
16th to endDay
7%21231335%6%62%
2306
September1st to 15thDay
8%312322246%61%
2145
16th to endDay
8%212212346%63%
1980
October1st to 15thDay
13%414323446%51%
1895
16th to endDay
7%41443445%6%54%
1743
November1st to 15thDay
6%425%42345%7%51%
1718
16th to endDay
5%6%2442445%6%51%
1670
December1st to 15thDay
5%7%46%3245%6%6%46%
1560
16th to endDay
9%9%36%424447%43%
1664
January1st to 15thNight
5%5%37%5%345%5%7%44%
2716
16th to endNight
48%35%5%3445%7%47%
2758
February1st to 15thNight
8%8%45%5%24447%43%
2256
16th to endNight
6%8%35%6%2446%6%45%
1894
March1st to 15thNight
8%7%25%42446%7%46%
2147
16th to endNight
11%6%25%4245%5%9%41%
2019
April1st to 15thNight
12%5%25%3345%47%43%
1798
16th to endNight
19%6%24433446%39%
1689
May1st to 15thNight
11%5%244245%6%7%46%
1566
16th to endNight
15%4144235%6%6%43%
1497
June1st to 15thNight
13%22442445%8%46%
1440
16th to endNight
42134245%7%7%56%
1440
July1st to 15thNight
5%21342445%8%58%
1440
16th to endNight
1223245%6%7%62%
1512
August1st to 15thNight
4213425%46%8%54%
1513
16th to endNight
4212323437%64%
1895
September1st to 15thNight
7%21332345%5%60%
1815
16th to endNight
8%212213335%64%
1980
October1st to 15thNight
15%5%13324346%49%
2064
16th to endNight
9%414423446%53%
2467
November1st to 15thNight
8%6%2442345%8%50%
2470
16th to endNight
6%5%25%32445%7%52%
2616
December1st to 15thNight
5%8%36%5%345%47%45%
2730
16th to endNight
6%7%36%5%25%447%45%
2912

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
5%5%38%6%3445%8%44%
1552
16th to endDay
47%344345%5%8%48%
1570
February1st to 15thDay
7%10%45%6%24446%42%
1610
16th to endDay
47%25%5%3446%8%45%
1580
March1st to 15thDay
6%435%41445%7%51%
1800
16th to endDay
10%6%244246%6%9%40%
2202
April1st to 15thDay
11%6%3442445%8%43%
2150
16th to endDay
16%6%3443445%8%38%
2269
May1st to 15thDay
13%6%2442346%7%45%
2384
16th to endDay
15%6%244245%6%8%39%
2616
June1st to 15thDay
11%3133245%6%9%47%
2520
16th to endDay
321232346%8%61%
2520
July1st to 15thDay
5%21332347%8%56%
2520
16th to endDay
421232445%7%60%
2656
August1st to 15thDay
441343447%10%51%
2445
16th to endDay
7%21231335%6%61%
2306
September1st to 15thDay
8%312323246%61%
2145
16th to endDay
8%212212346%63%
1980
October1st to 15thDay
12%5%24323447%50%
1895
16th to endDay
7%414435%45%6%54%
1743
November1st to 15thDay
6%5%15%5%2445%7%51%
1718
16th to endDay
5%6%2442445%7%51%
1670
December1st to 15thDay
5%8%37%32446%6%46%
1560
16th to endDay
9%10%36%424447%43%
1664
January1st to 15thNight
5%6%37%5%345%5%7%44%
2716
16th to endNight
47%35%5%3445%7%47%
2758
February1st to 15thNight
7%9%35%5%24448%43%
2249
16th to endNight
6%8%36%6%2436%7%45%
1894
March1st to 15thNight
7%7%25%4245%6%7%46%
2160
16th to endNight
11%7%25%4245%6%9%41%
2019
April1st to 15thNight
12%5%35%335%5%5%7%43%
1798
16th to endNight
18%7%3443345%6%38%
1689
May1st to 15thNight
10%5%143345%6%7%46%
1565
16th to endNight
15%4144235%7%6%43%
1497
June1st to 15thNight
13%32442436%8%46%
1440
16th to endNight
42134245%6%7%56%
1440
July1st to 15thNight
5%21332445%8%58%
1440
16th to endNight
1223245%5%7%63%
1512
August1st to 15thNight
32134245%5%8%54%
1513
16th to endNight
4313323437%64%
1895
September1st to 15thNight
7%313323346%60%
1815
16th to endNight
8%213213336%64%
1980
October1st to 15thNight
15%5%13324346%48%
2064
16th to endNight
9%414424446%53%
2467
November1st to 15thNight
7%6%2442335%8%50%
2470
16th to endNight
6%5%2433445%8%51%
2616
December1st to 15thNight
5%8%36%5%345%47%45%
2730
16th to endNight
6%8%36%5%24448%45%
2912

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
6%5%37%6%345%5%7%44%
1552
16th to endDay
47%3443445%8%48%
1570
February1st to 15thDay
7%10%45%6%24446%41%
1610
16th to endDay
5%6%35%5%35%36%7%46%
1580
March1st to 15thDay
5%5%36%42345%7%51%
1800
16th to endDay
11%6%24435%5%6%8%41%
2200
April1st to 15thDay
12%6%2442345%8%44%
2150
16th to endDay
16%6%2442445%8%38%
2269
May1st to 15thDay
13%6%2442346%6%46%
2384
16th to endDay
15%6%244245%6%8%39%
2616
June1st to 15thDay
11%323325%46%9%47%
2520
16th to endDay
31232446%8%62%
2520
July1st to 15thDay
6%21332347%8%56%
2520
16th to endDay
421332445%8%59%
2656
August1st to 15thDay
5%31442446%10%51%
2445
16th to endDay
7%31231335%6%61%
2306
September1st to 15thDay
9%212323346%61%
2145
16th to endDay
8%212212346%63%
1980
October1st to 15thDay
12%5%24323346%51%
1895
16th to endDay
7%41443435%6%53%
1743
November1st to 15thDay
6%4245%3345%7%51%
1718
16th to endDay
5%6%244245%5%6%51%
1670
December1st to 15thDay
6%7%5%6%41446%6%45%
1560
16th to endDay
9%9%36%434348%42%
1664
January1st to 15thNight
5%6%37%5%345%5%7%44%
2716
16th to endNight
47%36%5%3445%7%47%
2758
February1st to 15thNight
7%8%45%5%2445%7%43%
2249
16th to endNight
6%7%35%5%2445%6%45%
1894
March1st to 15thNight
8%6%25%4245%5%7%46%
2160
16th to endNight
10%7%25%425%5%5%9%41%
2019
April1st to 15thNight
12%6%24435%5%47%43%
1798
16th to endNight
18%6%3442445%6%39%
1689
May1st to 15thNight
11%414425%45%8%46%
1565
16th to endNight
15%4244236%7%6%43%
1497
June1st to 15thNight
13%3243245%48%46%
1440
16th to endNight
42133345%7%7%56%
1440
July1st to 15thNight
5%21332446%7%58%
1440
16th to endNight
11123245%6%8%62%
1512
August1st to 15thNight
32235%345%6%8%54%
1513
16th to endNight
4212213446%64%
1895
September1st to 15thNight
7%21322345%6%60%
1815
16th to endNight
8%22212335%65%
1980
October1st to 15thNight
15%5%13424346%49%
2064
16th to endNight
9%41442445%6%52%
2467
November1st to 15thNight
8%6%2442345%7%51%
2470
16th to endNight
6%5%244235%5%7%52%
2616
December1st to 15thNight
6%7%46%5%345%5%6%45%
2730
16th to endNight
6%7%36%5%2445%7%45%
2912

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
37%7%18%26%8%1
1553
16th to endDay
32%8%21%24%11%1
1570
February1st to 15thDay
42%7%16%22%9%2
1611
16th to endDay
35%7%18%24%10%3
1580
March1st to 15thDay
31%6%16%30%12%1
1800
16th to endDay
37%8%18%25%9%
2202
April1st to 15thDay
37%6%16%30%7%1
2150
16th to endDay
43%7%15%22%10%
2269
May1st to 15thDay
36%6%16%28%11%
2384
16th to endDay
40%9%18%21%8%1
2620
June1st to 15thDay
32%7%18%26%13%1
2520
16th to endDay
17%6%15%32%20%7%
2520
July1st to 15thDay
23%7%13%23%24%7%
2371
16th to endDay
20%5%10%27%23%11%
2489
August1st to 15thDay
25%7%17%26%16%6%
2429
16th to endDay
22%410%29%22%10%
2306
September1st to 15thDay
24%410%26%23%9%
2145
16th to endDay
21%310%34%26%3
1980
October1st to 15thDay
34%6%12%23%19%4
1895
16th to endDay
28%6%14%28%16%5%
1743
November1st to 15thDay
30%5%13%25%19%5%
1718
16th to endDay
30%5%17%29%14%2
1670
December1st to 15thDay
36%6%18%24%13%
1560
16th to endDay
40%5%17%22%12%
1664
January1st to 15thNight
36%8%17%24%11%2
2716
16th to endNight
34%6%18%23%15%1
2758
February1st to 15thNight
40%6%17%24%9%1
2259
16th to endNight
37%5%16%26%10%4
1894
March1st to 15thNight
34%6%17%25%15%1
2160
16th to endNight
38%7%17%23%11%1
2019
April1st to 15thNight
39%7%14%25%11%2
1798
16th to endNight
43%7%14%21%12%1
1689
May1st to 15thNight
35%6%14%29%11%1
1566
16th to endNight
37%9%16%23%10%1
1498
June1st to 15thNight
35%7%18%24%12%1
1440
16th to endNight
21%7%18%27%18%5%
1440
July1st to 15thNight
23%415%25%22%8%
1360
16th to endNight
16%7%14%26%23%12%
1416
August1st to 15thNight
23%8%14%26%20%6%
1505
16th to endNight
20%410%28%26%9%
1895
September1st to 15thNight
24%412%23%26%8%
1815
16th to endNight
22%310%31%25%5%
1980
October1st to 15thNight
35%5%10%22%18%6%
2064
16th to endNight
31%5%13%23%20%5%
2467
November1st to 15thNight
31%414%23%20%5%
2470
16th to endNight
30%5%15%26%17%3
2616
December1st to 15thNight
37%6%15%25%12%1
2730
16th to endNight
37%7%17%22%13%1
2912

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
10%21%43%17%6%
135
16th to endDay
8%124%36%22%5%
109
February1st to 15thDay
11%5%37%38%6%
90
16th to endDay
6%16%34%25%13%3
81
March1st to 15thDay
38%42%31%10%4
90
16th to endDay
18%10%26%26%15%2
216
April1st to 15thDay
11%11%40%29%6%
269
16th to endDay
24%8%22%27%14%2
379
May1st to 15thDay
15%7%27%26%19%2
468
16th to endDay
18%5%30%28%13%3
517
June1st to 15thDay
9%5%28%30%20%5%
495
16th to endDay
4428%41%18%2
495
July1st to 15thDay
6%221%39%27%2
475
16th to endDay
4119%42%28%2
515
August1st to 15thDay
5%221%43%24%3
493
16th to endDay
7%419%29%26%12%
346
September1st to 15thDay
9%5%24%27%26%8%
300
16th to endDay
8%6%25%32%22%4
135
October1st to 15thDay
17%35%28%10%7%
135
16th to endDay
11%13%25%23%22%3
144
November1st to 15thDay
8%228%32%21%5%
135
16th to endDay
17%9%32%31%8%
135
December1st to 15thDay
8%8%35%33%11%2
135
16th to endDay
13%5%35%34%9%1
144
January1st to 15thNight
8%8%31%38%12%
975
16th to endNight
9%8%34%38%7%
985
February1st to 15thNight
10%6%36%36%9%
743
16th to endNight
10%5%36%35%10%
632
March1st to 15thNight
10%5%30%41%10%
720
16th to endNight
14%6%30%39%9%
606
April1st to 15thNight
14%6%34%37%6%
539
16th to endNight
20%7%27%32%10%
540
May1st to 15thNight
13%7%29%37%12%
540
16th to endNight
15%6%32%34%11%
563
June1st to 15thNight
13%5%29%39%10%1
540
16th to endNight
4435%45%11%
540
July1st to 15thNight
6%123%47%19%
510
16th to endNight
2123%54%18%
564
August1st to 15thNight
4125%51%16%
539
16th to endNight
4222%48%20%
573
September1st to 15thNight
7%228%40%19%1
540
16th to endNight
9%326%39%19%
537
October1st to 15thNight
18%5%26%35%13%
624
16th to endNight
13%6%26%38%14%
931
November1st to 15thNight
11%6%31%39%9%1
950
16th to endNight
9%6%31%41%10%
975
December1st to 15thNight
9%7%34%38%8%
975
16th to endNight
10%6%30%40%10%
1040
Page generated at 2018-01-21 10:19:20. Version ac04

Copyright 2018 A. Danko


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