This page made possible by the sponsorship of: Michael Rosolina.

Twin Sugars Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Twin Sugars Observatory clear sky chart from 2005-11-05 to 2020-06-03.

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
38%
19387
16%
58083
10%
19349
44%
19349
18%
40635

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
16%
898
13%
2912
5%
896
25%
896
8%
2199
January16th to endNight
16%
960
13%
3120
5%
960
27%
960
10%
2312
February1st to 15thNight
17%
881
11%
2872
5%
881
26%
881
11%
2091
February16th to endNight
14%
791
14%
2368
5%
791
24%
791
11%
1807
March1st to 15thNight
21%
900
14%
2475
6%
900
28%
900
14%
1816
March16th to endNight
25%
960
13%
2640
7%
960
30%
960
14%
1980
April1st to 15thNight
27%
898
13%
2351
5%
898
33%
898
19%
1699
April16th to endNight
37%
756
17%
2092
8%
756
43%
756
21%
1450
May1st to 15thNight
38%
675
12%
2025
7%
675
42%
675
18%
1442
May16th to endNight
49%
705
12%
2116
8%
705
51%
705
20%
1496
June1st to 15thNight
60%
637
13%
1913
11%
637
64%
637
26%
1255
June16th to endNight
61%
630
15%
1890
12%
630
64%
630
27%
1204
July1st to 15thNight
60%
600
11%
1800
10%
600
61%
600
23%
1218
July16th to endNight
69%
660
15%
1883
12%
627
71%
627
30%
1181
August1st to 15thNight
65%
620
17%
1850
14%
617
65%
617
26%
1253
August16th to endNight
66%
763
18%
2101
14%
763
68%
763
32%
1345
September1st to 15thNight
60%
840
21%
2212
15%
840
62%
840
30%
1468
September16th to endNight
52%
837
19%
2310
16%
837
55%
837
26%
1552
October1st to 15thNight
49%
840
21%
2498
19%
840
55%
840
24%
1638
October16th to endNight
35%
896
22%
2688
15%
896
45%
896
20%
1768
November1st to 15thNight
40%
880
21%
2727
16%
880
49%
880
22%
1773
November16th to endNight
30%
900
19%
2970
12%
900
39%
900
16%
1999
December1st to 15thNight
22%
900
10%
3150
7%
900
27%
900
9%
2373
December16th to endNight
21%
960
15%
3120
7%
960
32%
960
11%
2316

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%7%36%6%35%5%5%7%32%
58303
Night
13%6%36%5%35%5%5%7%36%
58276
Cloud CoverDay
15%7%36%6%35%5%5%7%33%
58313
Night
13%6%35%5%35%5%5%7%37%
58280
TransparencyDay
49%9%11%17%11%1
58014
Night
44%9%12%18%12%1
58083
SeeingDay
23%15%23%19%12%6%
9087
Night
20%14%21%25%15%1
19394

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
15%8%410%9%45%445%27%
2016
16th to endDay
14%10%5%7%6%3445%5%32%
2160
February1st to 15thDay
14%8%39%6%35%5%5%7%29%
1980
16th to endDay
16%10%49%5%35%446%28%
1980
March1st to 15thDay
15%7%47%5%2445%6%35%
2464
16th to endDay
16%10%47%6%34346%32%
2640
April1st to 15thDay
13%6%36%6%34446%39%
2587
16th to endDay
18%6%36%5%345%5%5%35%
2814
May1st to 15thDay
18%7%36%6%345%5%7%29%
2916
16th to endDay
16%6%26%7%46%6%7%8%28%
3055
June1st to 15thDay
13%5%25%7%46%6%6%8%33%
2756
16th to endDay
10%5%36%7%47%6%7%8%31%
2730
July1st to 15thDay
13%6%36%7%46%5%5%8%30%
2730
16th to endDay
11%6%36%7%5%6%6%7%9%27%
2881
August1st to 15thDay
16%6%36%7%46%7%7%9%24%
2682
16th to endDay
11%5%27%7%5%7%6%7%8%29%
2791
September1st to 15thDay
16%6%25%5%345%5%7%36%
2405
16th to endDay
20%7%25%5%35%5%46%32%
2310
October1st to 15thDay
18%6%145%24447%39%
2122
16th to endDay
17%7%25%333436%42%
2240
November1st to 15thDay
13%6%25%5%345%47%41%
2117
16th to endDay
13%8%36%6%35%445%38%
1974
December1st to 15thDay
17%11%46%6%3445%5%29%
1800
16th to endDay
18%10%38%5%34446%29%
2153
January1st to 15thNight
16%7%39%8%45%5%6%6%27%
2912
16th to endNight
15%8%5%7%6%35%45%7%30%
3120
February1st to 15thNight
14%5%48%6%35%5%5%8%30%
2870
16th to endNight
14%8%49%6%36%5%5%6%27%
2368
March1st to 15thNight
15%7%26%7%45%6%5%6%33%
2463
16th to endNight
15%7%36%6%35%6%6%6%32%
2640
April1st to 15thNight
12%7%36%6%35%46%8%35%
2351
16th to endNight
15%6%24435%46%7%39%
2092
May1st to 15thNight
15%8%36%5%3445%7%36%
2025
16th to endNight
15%6%15%5%25%45%8%36%
2114
June1st to 15thNight
10%415%425%6%6%10%42%
1913
16th to endNight
9%4235%25%5%7%10%42%
1890
July1st to 15thNight
10%5%25%6%345%5%8%40%
1890
16th to endNight
5%3245%25%5%7%11%43%
1991
August1st to 15thNight
12%3235%46%5%6%9%39%
1861
16th to endNight
10%5%2442346%8%46%
2101
September1st to 15thNight
12%41442446%7%46%
2212
16th to endNight
17%6%245%2445%7%41%
2310
October1st to 15thNight
14%6%24424346%44%
2498
16th to endNight
13%5%26%5%34446%42%
2688
November1st to 15thNight
12%6%25%5%245%5%6%41%
2727
16th to endNight
14%6%35%5%345%48%37%
2970
December1st to 15thNight
16%8%48%7%46%5%47%26%
3150
16th to endNight
16%8%27%6%35%5%5%8%29%
3120

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
15%8%5%9%9%45%446%27%
2016
16th to endDay
14%9%5%6%6%3445%5%33%
2160
February1st to 15thDay
14%8%38%7%35%5%5%7%30%
1980
16th to endDay
15%10%49%6%35%446%28%
1980
March1st to 15thDay
15%7%37%5%3345%6%35%
2475
16th to endDay
17%9%47%6%33347%32%
2639
April1st to 15thDay
13%6%45%5%34446%39%
2587
16th to endDay
18%6%26%5%35%5%5%5%35%
2814
May1st to 15thDay
18%7%36%6%346%5%7%29%
2916
16th to endDay
15%5%36%6%47%5%6%8%29%
3055
June1st to 15thDay
13%426%6%47%5%6%8%34%
2756
16th to endDay
10%5%36%7%5%7%6%7%9%31%
2730
July1st to 15thDay
12%6%36%7%36%6%6%8%31%
2730
16th to endDay
11%6%36%7%46%7%8%9%28%
2881
August1st to 15thDay
16%6%36%7%5%6%6%7%9%24%
2682
16th to endDay
10%5%27%7%47%7%7%9%30%
2791
September1st to 15thDay
15%5%25%6%35%6%47%37%
2405
16th to endDay
19%6%25%6%35%5%5%6%33%
2310
October1st to 15thDay
17%6%15%43345%7%39%
2122
16th to endDay
17%8%24423346%43%
2240
November1st to 15thDay
12%6%25%5%345%48%42%
2117
16th to endDay
14%7%36%6%345%46%39%
1974
December1st to 15thDay
17%11%36%5%345%5%6%30%
1800
16th to endDay
18%10%37%6%345%46%29%
2153
January1st to 15thNight
16%6%39%8%46%5%5%7%27%
2912
16th to endNight
14%8%46%6%35%45%6%31%
3120
February1st to 15thNight
14%6%47%6%35%5%5%8%32%
2863
16th to endNight
14%7%5%8%7%36%6%6%5%28%
2368
March1st to 15thNight
14%6%26%7%446%5%6%34%
2475
16th to endNight
15%7%36%6%446%6%5%33%
2640
April1st to 15thNight
12%6%36%6%35%45%8%36%
2351
16th to endNight
14%5%245%35%46%7%39%
2092
May1st to 15thNight
14%8%36%5%3445%7%36%
2024
16th to endNight
15%5%25%5%245%5%9%37%
2114
June1st to 15thNight
10%3244246%7%10%43%
1913
16th to endNight
8%4234345%7%11%43%
1890
July1st to 15thNight
9%5%25%6%3446%8%41%
1890
16th to endNight
6%3235%35%6%6%12%44%
1991
August1st to 15thNight
12%4145%46%5%6%8%40%
1861
16th to endNight
9%5%15%4245%5%8%47%
2101
September1st to 15thNight
12%41442446%7%46%
2212
16th to endNight
16%5%3442345%6%42%
2310
October1st to 15thNight
14%6%25%42345%6%44%
2498
16th to endNight
13%6%25%5%35%446%43%
2688
November1st to 15thNight
13%6%25%42445%6%43%
2727
16th to endNight
14%5%345%35%45%8%38%
2970
December1st to 15thNight
16%7%47%7%46%6%47%27%
3150
16th to endNight
16%7%26%6%45%5%5%8%30%
3120

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
58%8%9%13%9%1
2017
16th to endDay
52%9%9%15%11%1
2160
February1st to 15thDay
53%7%9%17%9%1
1982
16th to endDay
57%7%9%15%8%1
1980
March1st to 15thDay
47%8%10%19%10%2
2475
16th to endDay
52%8%9%17%11%1
2640
April1st to 15thDay
44%8%11%19%12%3
2587
16th to endDay
48%8%10%16%13%2
2814
May1st to 15thDay
53%10%11%15%8%1
2916
16th to endDay
50%11%14%15%6%1
3059
June1st to 15thDay
45%10%13%19%11%
2756
16th to endDay
46%12%12%16%11%
2730
July1st to 15thDay
47%12%11%14%12%2
2591
16th to endDay
46%13%11%17%10%
2726
August1st to 15thDay
51%12%13%14%7%
2669
16th to endDay
46%12%13%17%8%1
2791
September1st to 15thDay
43%9%12%16%15%2
2405
16th to endDay
50%7%9%17%13%
2310
October1st to 15thDay
43%7%12%19%13%3
2122
16th to endDay
44%5%9%22%15%2
2240
November1st to 15thDay
40%7%10%18%17%4
2117
16th to endDay
45%8%9%19%14%1
1974
December1st to 15thDay
53%8%9%15%11%1
1800
16th to endDay
55%7%9%17%8%1
2153
January1st to 15thNight
56%8%9%13%9%2
2912
16th to endNight
52%9%10%14%10%1
3120
February1st to 15thNight
49%10%12%16%9%1
2872
16th to endNight
54%9%10%15%7%2
2368
March1st to 15thNight
49%8%11%18%10%1
2475
16th to endNight
49%11%10%16%11%1
2640
April1st to 15thNight
45%9%12%17%12%2
2351
16th to endNight
42%8%13%18%13%3
2092
May1st to 15thNight
46%10%15%16%11%
2025
16th to endNight
43%11%17%19%6%1
2116
June1st to 15thNight
34%13%17%20%12%
1913
16th to endNight
32%13%17%24%11%
1890
July1st to 15thNight
39%12%14%17%13%3
1800
16th to endNight
29%13%18%24%12%1
1883
August1st to 15thNight
38%10%16%21%11%
1850
16th to endNight
33%10%16%26%11%1
2101
September1st to 15thNight
34%11%14%19%17%2
2212
16th to endNight
40%7%12%23%14%
2310
October1st to 15thNight
39%7%11%23%14%3
2498
16th to endNight
41%7%9%22%16%2
2688
November1st to 15thNight
41%6%11%17%17%5%
2727
16th to endNight
45%7%11%17%15%2
2970
December1st to 15thNight
56%9%10%13%8%1
3150
16th to endNight
53%9%11%15%9%1
3120

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
36%29%22%8%2
225
16th to endDay
41%22%25%7%2
240
February1st to 15thDay
40%27%24%7%
225
16th to endDay
33%24%30%9%1
233
March1st to 15thDay
30%29%20%16%4
450
16th to endDay
28%24%24%16%5%
480
April1st to 15thDay
23%24%26%16%7%1
450
16th to endDay
29%17%24%12%11%3
439
May1st to 15thDay
25%19%26%13%10%4
468
16th to endDay
20%11%26%19%14%8%
523
June1st to 15thDay
15%9%26%23%15%9%
443
16th to endDay
11%11%31%22%13%9%
435
July1st to 15thDay
14%5%24%25%16%13%
425
16th to endDay
11%319%29%20%15%
454
August1st to 15thDay
19%418%22%20%14%
418
16th to endDay
11%316%28%23%17%
460
September1st to 15thDay
16%6%16%22%23%13%
435
16th to endDay
20%7%16%27%21%7%
434
October1st to 15thDay
21%8%20%24%20%4
435
16th to endDay
25%17%24%18%12%1
464
November1st to 15thDay
25%16%24%23%9%1
355
16th to endDay
25%22%27%19%4
208
December1st to 15thDay
40%28%12%14%31
150
16th to endDay
38%21%22%14%2
238
January1st to 15thNight
32%24%23%16%3
900
16th to endNight
30%23%26%18%1
960
February1st to 15thNight
30%22%26%18%2
884
16th to endNight
25%27%28%17%1
791
March1st to 15thNight
25%21%28%21%3
900
16th to endNight
21%20%28%21%7%
960
April1st to 15thNight
20%19%29%24%5%
898
16th to endNight
20%13%23%29%12%
756
May1st to 15thNight
20%11%25%28%14%1
675
16th to endNight
17%7%17%28%25%3
707
June1st to 15thNight
10%417%33%30%2
637
16th to endNight
11%316%37%27%3
630
July1st to 15thNight
13%212%34%32%4
600
16th to endNight
6%310%30%41%7%
660
August1st to 15thNight
15%10%37%32%3
620
16th to endNight
12%110%30%37%6%
763
September1st to 15thNight
14%313%30%31%6%
840
16th to endNight
19%6%13%27%28%3
837
October1st to 15thNight
16%10%17%30%22%2
840
16th to endNight
19%18%22%23%14%1
896
November1st to 15thNight
19%14%22%30%12%1
880
16th to endNight
23%18%23%26%8%
900
December1st to 15thNight
26%23%23%21%5%
900
16th to endNight
28%19%25%22%3
960
Page generated at 2020-06-04 03:18:56. Version ac04

Copyright 2020 A. Danko


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