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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 2017-09-10.

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%
14628
13%
46786
8%
14596
37%
14596
17%
33371

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%
720
6%
2506
3%
716
21%
716
7%
2041
January16th to endNight
21%
768
11%
2637
7%
768
27%
768
12%
1954
February1st to 15thNight
18%
704
10%
2287
4%
701
26%
701
11%
1753
February16th to endNight
23%
631
13%
1952
6%
631
33%
631
13%
1459
March1st to 15thNight
21%
720
13%
2097
7%
720
28%
720
15%
1571
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
45%
700
15%
1750
8%
700
48%
700
29%
1215
September16th to endNight
46%
657
21%
1795
14%
657
51%
657
31%
1150
October1st to 15thNight
33%
660
17%
1980
11%
660
42%
660
20%
1382
October16th to endNight
26%
704
11%
2197
6%
704
33%
704
13%
1681
November1st to 15thNight
27%
700
17%
2334
12%
700
35%
700
16%
1649
November16th to endNight
20%
720
10%
2520
6%
720
26%
720
10%
1952
December1st to 15thNight
18%
720
6%
2520
3%
720
23%
720
8%
2023
December16th to endNight
14%
768
9%
2688
4%
768
21%
768
8%
2161

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%6%35%45%6%33%
47854
Night
17%9%46%5%34446%32%
46955
Cloud CoverDay
18%7%36%5%34446%34%
47863
Night
18%9%36%5%34445%34%
46961
TransparencyDay
50%6%12%19%9%1
47541
Night
52%5%11%19%9%
46786
SeeingDay
21%12%29%22%11%3
5446
Night
22%10%29%26%10%
14628

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
21%13%5%9%7%25%345%21%
1432
16th to endDay
14%14%5%7%7%45%446%24%
1584
February1st to 15thDay
12%14%5%10%7%45%5%5%424%
1575
16th to endDay
16%13%37%7%35%5%45%27%
1521
March1st to 15thDay
16%10%47%7%45%5%5%428%
1852
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%5%25%5%2445%7%40%
2098
16th to endDay
14%5%23434448%43%
1834
October1st to 15thDay
20%7%25%5%25%5%5%6%33%
1650
16th to endDay
25%8%37%6%345%36%25%
1674
November1st to 15thDay
16%8%35%5%36%46%6%33%
1524
16th to endDay
22%11%48%6%35%345%24%
1440
December1st to 15thDay
20%14%5%7%7%46%5%46%17%
1440
16th to endDay
24%13%5%8%7%2433421%
1536
January1st to 15thNight
18%14%6%10%8%35%44419%
2506
16th to endNight
12%16%5%8%6%35%336%26%
2637
February1st to 15thNight
13%12%5%11%7%35%446%23%
2285
16th to endNight
17%11%48%7%3445%5%28%
1952
March1st to 15thNight
18%10%5%8%6%24335%30%
2084
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%26%43445%5%42%
1750
16th to endNight
15%5%24423335%48%
1795
October1st to 15thNight
19%7%25%5%24446%36%
1980
16th to endNight
24%8%36%6%4445%5%26%
2197
November1st to 15thNight
20%8%36%5%34445%32%
2334
16th to endNight
23%9%5%8%6%34445%24%
2520
December1st to 15thNight
22%13%5%7%5%35%5%45%19%
2520
16th to endNight
24%15%5%8%6%2433420%
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
21%13%5%9%6%3444422%
1432
16th to endDay
14%14%5%7%6%45%446%25%
1584
February1st to 15thDay
14%12%5%10%6%46%445%24%
1575
16th to endDay
18%12%47%6%35%445%27%
1521
March1st to 15thDay
22%8%36%7%35%5%4330%
1862
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%41%
2098
16th to endDay
15%42442435%7%44%
1834
October1st to 15thDay
20%7%25%5%35%446%33%
1650
16th to endDay
25%8%37%5%34435%26%
1674
November1st to 15thDay
16%8%35%5%35%5%46%35%
1524
16th to endDay
22%11%37%5%44346%26%
1440
December1st to 15thDay
21%14%48%7%35%5%46%17%
1440
16th to endDay
23%14%5%8%6%3343421%
1536
January1st to 15thNight
18%15%6%9%7%45%43419%
2506
16th to endNight
13%16%5%7%6%35%346%26%
2637
February1st to 15thNight
14%12%5%11%7%44445%25%
2278
16th to endNight
17%11%38%6%33445%28%
1952
March1st to 15thNight
25%9%45%6%2322432%
2097
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%42%
1750
16th to endNight
16%5%15%423245%49%
1795
October1st to 15thNight
20%7%25%42445%6%36%
1980
16th to endNight
25%8%36%6%34346%26%
2197
November1st to 15thNight
19%9%25%5%33345%37%
2334
16th to endNight
21%10%47%6%2344430%
2520
December1st to 15thNight
23%14%46%5%35%5%45%20%
2520
16th to endNight
25%14%5%7%6%33335%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
64%5%9%13%5%
1433
16th to endDay
60%5%13%12%7%
1584
February1st to 15thDay
61%6%10%16%3
1577
16th to endDay
58%6%10%14%8%1
1521
March1st to 15thDay
57%6%12%15%7%
1862
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
41%7%13%25%11%
2098
16th to endDay
39%7%12%31%9%
1834
October1st to 15thDay
49%6%14%19%8%
1650
16th to endDay
60%6%12%13%6%
1674
November1st to 15thDay
49%6%15%19%8%
1524
16th to endDay
61%5%12%12%5%1
1440
December1st to 15thDay
67%7%11%11%2
1440
16th to endDay
67%411%10%5%
1536
January1st to 15thNight
68%6%8%11%5%
2506
16th to endNight
58%5%11%16%7%
2637
February1st to 15thNight
61%5%11%16%5%
2287
16th to endNight
57%5%9%18%8%
1952
March1st to 15thNight
57%410%19%7%
2097
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
42%6%11%28%10%
1750
16th to endNight
38%411%34%10%
1795
October1st to 15thNight
48%5%11%22%11%
1980
16th to endNight
58%6%12%16%6%
2197
November1st to 15thNight
52%5%13%17%10%
2334
16th to endNight
62%5%10%16%4
2520
December1st to 15thNight
65%7%12%12%2
2520
16th to endNight
67%49%12%4
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
30%21%26%18%3
60
16th to endDay
27%16%37%15%2
72
February1st to 15thDay
30%25%31%13%
90
16th to endDay
30%23%22%19%4
180
March1st to 15thDay
25%14%33%21%5%
270
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
19%7%24%17%20%10%
294
16th to endDay
18%7%29%21%15%8%
254
October1st to 15thDay
22%9%27%22%14%2
255
16th to endDay
29%17%26%19%7%
256
November1st to 15thDay
17%12%32%23%12%2
178
16th to endDay
31%15%31%20%1
60
December1st to 15thDay
21%18%41%15%3
60
16th to endDay
42%17%35%4
64
January1st to 15thNight
24%16%32%21%4
720
16th to endNight
22%12%34%24%5%
768
February1st to 15thNight
20%14%38%21%5%
704
16th to endNight
24%14%32%22%5%
631
March1st to 15thNight
25%14%33%24%2
720
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%26%29%19%1
700
16th to endNight
18%7%24%27%20%2
657
October1st to 15thNight
24%9%27%25%11%1
660
16th to endNight
29%12%25%24%7%
704
November1st to 15thNight
24%11%31%21%11%
700
16th to endNight
29%16%25%19%8%
720
December1st to 15thNight
30%13%31%21%3
720
16th to endNight
33%12%30%17%4
768
Page generated at 2017-09-11 19:35:15. Version ac04

Copyright 2017 A. Danko


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