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SmartScope
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the SmartScope clear sky chart from 2005-11-05 to 2018-03-11.

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%
15356
13%
49141
8%
15324
37%
15324
16%
35057

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
17%
780
7%
2716
3%
776
22%
776
7%
2200
January16th to endNight
21%
832
11%
2857
6%
832
26%
832
11%
2126
February1st to 15thNight
17%
764
11%
2482
3%
761
26%
761
11%
1890
February16th to endNight
23%
683
13%
2113
6%
683
33%
683
13%
1575
March1st to 15thNight
20%
764
12%
2228
7%
764
27%
764
14%
1696
March16th to endNight
30%
768
19%
2036
9%
768
38%
768
22%
1397
April1st to 15thNight
24%
718
15%
1796
6%
718
29%
718
19%
1315
April16th to endNight
31%
645
17%
1725
8%
645
37%
645
22%
1216
May1st to 15thNight
35%
360
17%
1440
15%
360
44%
360
17%
946
May16th to endNight
36%
375
13%
1497
10%
374
47%
374
19%
962
June1st to 15thNight
36%
360
9%
1440
8%
360
46%
360
16%
969
June16th to endNight
41%
360
8%
1440
12%
360
46%
360
18%
922
July1st to 15thNight
54%
340
14%
1360
20%
340
60%
340
28%
745
July16th to endNight
57%
376
14%
1418
17%
354
61%
354
26%
801
August1st to 15thNight
53%
446
14%
1517
12%
444
58%
444
25%
954
August16th to endNight
52%
708
19%
1854
10%
708
57%
708
36%
1153
September1st to 15thNight
47%
720
16%
1800
8%
720
49%
720
29%
1239
September16th to endNight
49%
717
23%
1959
15%
717
54%
717
32%
1244
October1st to 15thNight
34%
720
17%
2160
11%
720
43%
720
21%
1482
October16th to endNight
25%
768
12%
2397
6%
768
33%
768
13%
1820
November1st to 15thNight
27%
760
16%
2534
11%
760
35%
760
16%
1790
November16th to endNight
20%
780
10%
2730
6%
780
26%
780
10%
2110
December1st to 15thNight
18%
780
7%
2730
3%
780
23%
780
8%
2184
December16th to endNight
13%
832
10%
2912
3%
832
22%
832
8%
2321

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
16%8%36%6%35%45%6%33%
49500
Night
17%9%46%5%34446%32%
49310
Cloud CoverDay
18%7%36%5%34446%34%
49509
Night
18%9%36%5%34445%33%
49316
TransparencyDay
50%6%12%19%9%1
49187
Night
52%5%11%19%9%
49141
SeeingDay
21%12%29%21%11%3
5975
Night
22%10%29%26%10%
15356

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%13%5%9%7%35%44421%
1552
16th to endDay
14%13%5%8%7%45%445%24%
1716
February1st to 15thDay
12%14%5%10%7%45%5%5%424%
1710
16th to endDay
17%13%36%7%345%45%26%
1646
March1st to 15thDay
17%11%5%7%7%45%5%4327%
1958
16th to endDay
15%7%35%42435%6%40%
2187
April1st to 15thDay
22%8%36%423346%34%
2152
16th to endDay
20%7%35%5%23445%37%
2244
May1st to 15thDay
18%7%35%6%35%446%33%
2511
16th to endDay
17%6%25%6%35%45%7%35%
2618
June1st to 15thDay
20%6%345%35%5%47%30%
2520
16th to endDay
16%6%26%5%35%6%6%8%31%
2520
July1st to 15thDay
12%5%245%36%5%6%8%39%
2520
16th to endDay
11%425%5%35%5%7%9%38%
2654
August1st to 15thDay
9%6%25%6%46%5%6%8%38%
2432
16th to endDay
10%5%25%5%35%5%5%9%41%
2336
September1st to 15thDay
15%425%5%2445%7%42%
2160
16th to endDay
13%5%24434448%45%
2000
October1st to 15thDay
19%7%25%5%25%45%6%34%
1800
16th to endDay
24%8%37%6%345%36%26%
1826
November1st to 15thDay
16%8%35%5%36%45%6%32%
1654
16th to endDay
22%11%47%6%35%45%424%
1560
December1st to 15thDay
19%14%5%8%7%36%5%46%17%
1560
16th to endDay
23%13%5%8%7%2433422%
1664
January1st to 15thNight
18%13%6%10%8%35%44419%
2716
16th to endNight
13%16%5%8%6%35%336%26%
2857
February1st to 15thNight
12%13%5%11%7%35%446%24%
2480
16th to endNight
17%10%48%6%3445%5%28%
2113
March1st to 15thNight
19%12%5%8%7%2433428%
2215
16th to endNight
15%6%45%5%3434442%
2036
April1st to 15thNight
22%8%345%33345%34%
1796
16th to endNight
17%8%26%5%34446%37%
1725
May1st to 15thNight
21%7%335%2445%6%35%
1440
16th to endNight
15%6%35%5%3346%7%37%
1495
June1st to 15thNight
17%5%36%6%3445%8%33%
1440
16th to endNight
16%5%245%25%5%6%7%37%
1440
July1st to 15thNight
10%323435%5%410%46%
1440
16th to endNight
9%424435%46%8%46%
1514
August1st to 15thNight
9%6%26%5%25%46%10%41%
1527
16th to endNight
9%4244245%5%7%49%
1854
September1st to 15thNight
14%5%25%43445%5%43%
1800
16th to endNight
15%5%24423335%49%
1959
October1st to 15thNight
18%7%25%5%24446%37%
2160
16th to endNight
23%8%36%5%34446%27%
2397
November1st to 15thNight
20%8%36%5%34445%33%
2534
16th to endNight
23%10%48%6%34345%24%
2730
December1st to 15thNight
21%14%5%7%5%345%46%19%
2730
16th to endNight
23%15%5%8%7%3433420%
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
21%13%5%9%6%3444421%
1552
16th to endDay
14%14%6%8%6%45%446%24%
1716
February1st to 15thDay
14%13%5%10%6%46%445%24%
1710
16th to endDay
19%12%37%5%35%45%5%26%
1646
March1st to 15thDay
22%9%36%7%345%4329%
1968
16th to endDay
21%7%24324345%40%
2186
April1st to 15thDay
21%8%35%413336%37%
2152
16th to endDay
18%6%25%5%23445%40%
2244
May1st to 15thDay
21%7%25%433435%36%
2511
16th to endDay
21%5%245%24446%37%
2618
June1st to 15thDay
20%5%35%435%5%46%34%
2520
16th to endDay
15%6%36%435%5%6%7%35%
2520
July1st to 15thDay
13%5%25%5%35%6%6%7%40%
2520
16th to endDay
11%4245%36%5%6%9%38%
2654
August1st to 15thDay
20%4245%3445%6%37%
2432
16th to endDay
18%42432445%8%40%
2336
September1st to 15thDay
15%425%5%33447%43%
2160
16th to endDay
14%42443435%7%45%
2000
October1st to 15thDay
20%7%26%5%35%446%34%
1800
16th to endDay
24%7%37%5%345%45%27%
1826
November1st to 15thDay
16%8%35%5%35%5%5%6%34%
1654
16th to endDay
21%11%37%6%44345%26%
1560
December1st to 15thDay
20%14%48%7%35%446%18%
1560
16th to endDay
23%14%5%8%6%34435%22%
1664
January1st to 15thNight
18%14%6%10%7%45%44420%
2716
16th to endNight
14%16%5%7%6%35%346%26%
2857
February1st to 15thNight
14%13%5%11%7%44445%25%
2473
16th to endNight
17%11%38%6%3445%5%28%
2113
March1st to 15thNight
24%11%45%6%2322430%
2228
16th to endNight
21%6%35%5%2433342%
2036
April1st to 15thNight
22%8%34423336%37%
1796
16th to endNight
17%7%25%433446%40%
1725
May1st to 15thNight
22%6%25%425%345%36%
1440
16th to endNight
18%5%35%43335%6%38%
1495
June1st to 15thNight
17%6%25%6%4445%7%35%
1440
16th to endNight
16%425%425%45%7%38%
1440
July1st to 15thNight
10%313435%5%5%9%46%
1440
16th to endNight
9%424435%5%6%7%46%
1514
August1st to 15thNight
14%5%26%42445%8%41%
1527
16th to endNight
15%314423445%49%
1854
September1st to 15thNight
14%5%26%434446%44%
1800
16th to endNight
15%5%14423245%49%
1959
October1st to 15thNight
19%6%25%324446%38%
2160
16th to endNight
24%7%45%6%34446%27%
2397
November1st to 15thNight
20%9%25%5%33345%37%
2534
16th to endNight
21%10%47%6%2344429%
2730
December1st to 15thNight
22%15%46%6%35%6%45%20%
2730
16th to endNight
24%14%5%7%6%33335%21%
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
65%5%9%13%5%
1553
16th to endDay
60%6%13%11%7%
1716
February1st to 15thDay
61%6%10%16%4
1712
16th to endDay
58%6%10%14%8%1
1646
March1st to 15thDay
59%6%11%15%7%
1968
16th to endDay
44%5%10%19%14%5%
2187
April1st to 15thDay
52%47%20%12%2
2152
16th to endDay
48%47%19%15%3
2244
May1st to 15thDay
50%5%8%20%13%2
2511
16th to endDay
47%7%11%19%11%1
2622
June1st to 15thDay
52%7%10%20%8%
2520
16th to endDay
47%7%13%19%10%1
2520
July1st to 15thDay
37%8%16%25%11%
2371
16th to endDay
41%9%17%22%9%
2487
August1st to 15thDay
41%9%16%21%9%
2418
16th to endDay
36%7%16%28%9%
2336
September1st to 15thDay
40%7%13%27%11%
2160
16th to endDay
38%7%12%32%9%
2000
October1st to 15thDay
49%6%14%20%8%
1800
16th to endDay
58%7%13%14%5%
1826
November1st to 15thDay
50%7%15%18%7%
1654
16th to endDay
62%6%12%12%5%1
1560
December1st to 15thDay
67%7%11%11%2
1560
16th to endDay
66%411%12%5%
1664
January1st to 15thNight
67%6%9%11%5%
2716
16th to endNight
59%5%11%16%7%
2857
February1st to 15thNight
61%411%16%5%
2482
16th to endNight
57%5%9%18%9%
2113
March1st to 15thNight
59%49%18%7%
2228
16th to endNight
45%310%19%16%4
2036
April1st to 15thNight
51%38%19%15%
1796
16th to endNight
47%5%7%19%16%3
1725
May1st to 15thNight
49%47%19%14%3
1440
16th to endNight
44%7%12%19%14%2
1497
June1st to 15thNight
48%6%12%21%9%1
1440
16th to endNight
43%8%12%20%14%
1440
July1st to 15thNight
32%6%14%30%14%
1360
16th to endNight
34%7%16%26%15%
1418
August1st to 15thNight
37%9%17%23%12%
1517
16th to endNight
32%6%16%32%11%
1854
September1st to 15thNight
41%6%11%28%10%
1800
16th to endNight
37%411%34%11%
1959
October1st to 15thNight
46%5%11%23%11%
2160
16th to endNight
57%6%12%17%5%
2397
November1st to 15thNight
52%5%13%17%9%
2534
16th to endNight
61%5%11%15%4
2730
December1st to 15thNight
64%7%12%11%3
2730
16th to endNight
67%49%13%5%
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
28%17%31%17%4
90
16th to endDay
27%17%37%13%2
108
February1st to 15thDay
28%24%34%12%
135
16th to endDay
31%25%22%17%3
227
March1st to 15thDay
28%14%33%18%4
312
16th to endDay
22%16%30%17%10%2
288
April1st to 15thDay
26%22%24%18%7%
270
16th to endDay
22%17%28%17%10%3
270
May1st to 15thDay
27%11%31%18%7%3
288
16th to endDay
18%14%34%18%11%1
331
June1st to 15thDay
25%8%32%23%8%2
315
16th to endDay
18%10%32%23%13%1
315
July1st to 15thDay
15%428%33%13%5%
305
16th to endDay
13%328%28%19%5%
326
August1st to 15thDay
13%6%22%32%17%6%
313
16th to endDay
11%5%27%26%17%11%
332
September1st to 15thDay
18%6%23%18%20%12%
315
16th to endDay
14%7%25%21%21%9%
314
October1st to 15thDay
22%9%28%22%13%3
315
16th to endDay
26%19%25%20%7%
312
November1st to 15thDay
21%12%30%23%10%1
218
16th to endDay
28%20%36%13%1
90
December1st to 15thDay
21%23%38%12%4
90
16th to endDay
37%22%30%9%
96
January1st to 15thNight
25%16%32%21%5%
780
16th to endNight
22%13%34%23%5%
832
February1st to 15thNight
21%14%39%20%4
764
16th to endNight
24%14%32%22%5%
683
March1st to 15thNight
25%14%33%23%2
764
16th to endNight
20%15%28%26%9%
768
April1st to 15thNight
26%13%31%24%4
718
16th to endNight
23%14%28%25%8%
645
May1st to 15thNight
25%6%26%30%9%1
360
16th to endNight
19%6%33%25%14%
375
June1st to 15thNight
21%5%29%33%9%
360
16th to endNight
20%327%35%12%1
360
July1st to 15thNight
11%225%43%16%
340
16th to endNight
9%325%45%15%1
376
August1st to 15thNight
13%220%39%23%1
446
16th to endNight
10%423%36%22%2
708
September1st to 15thNight
17%5%25%29%19%2
720
16th to endNight
17%6%22%26%23%2
717
October1st to 15thNight
23%8%27%25%12%1
720
16th to endNight
29%12%26%24%7%
768
November1st to 15thNight
25%10%30%21%10%
760
16th to endNight
29%16%26%18%8%
780
December1st to 15thNight
30%13%31%20%3
780
16th to endNight
32%13%31%17%3
832
Page generated at 2018-03-12 13:28:12. Version ac04

Copyright 2018 A. Danko


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