Stokes Starparty
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stokes Starparty clear sky chart from 2005-11-05 to 2017-09-24.

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%
15017
19%
46930
8%
14986
42%
14986
20%
30274

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
19%
720
19%
2506
6%
716
35%
716
15%
1612
January16th to endNight
15%
768
20%
2578
4%
768
33%
768
14%
1649
February1st to 15thNight
13%
704
16%
2258
2%
701
30%
701
14%
1499
February16th to endNight
16%
631
25%
1893
7%
631
39%
631
17%
1223
March1st to 15thNight
17%
720
19%
2124
6%
720
33%
720
16%
1406
March16th to endNight
19%
768
22%
2011
7%
768
31%
768
21%
1323
April1st to 15thNight
20%
718
16%
1796
4%
718
26%
718
19%
1280
April16th to endNight
27%
720
18%
1800
4%
720
35%
720
25%
1235
May1st to 15thNight
28%
462
19%
1542
11%
462
38%
462
18%
1021
May16th to endNight
37%
374
15%
1497
12%
374
46%
374
18%
920
June1st to 15thNight
45%
360
14%
1440
13%
360
54%
360
18%
901
June16th to endNight
51%
360
14%
1440
12%
360
61%
360
26%
815
July1st to 15thNight
53%
340
13%
1360
16%
340
57%
340
21%
826
July16th to endNight
58%
376
15%
1418
16%
354
64%
354
25%
801
August1st to 15thNight
53%
547
18%
1618
12%
545
57%
545
32%
999
August16th to endNight
55%
764
19%
1910
10%
764
57%
764
32%
1274
September1st to 15thNight
43%
720
23%
1800
10%
720
49%
720
32%
1178
September16th to endNight
49%
693
26%
1884
18%
693
55%
693
32%
1172
October1st to 15thNight
36%
660
21%
1961
15%
660
45%
660
23%
1286
October16th to endNight
26%
704
20%
2182
8%
704
42%
704
23%
1369
November1st to 15thNight
31%
700
21%
2277
10%
700
46%
700
21%
1410
November16th to endNight
27%
720
20%
2427
10%
720
40%
720
18%
1544
December1st to 15thNight
21%
720
14%
2520
6%
720
32%
720
12%
1712
December16th to endNight
16%
768
16%
2688
3%
768
32%
768
12%
1819

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%6%25%5%3445%7%37%
48002
Night
15%6%2442445%7%41%
47100
Cloud CoverDay
15%6%25%5%3445%7%38%
48011
Night
15%6%25%42445%7%41%
47106
TransparencyDay
44%6%11%21%14%1
47690
Night
41%5%12%22%15%1
46930
SeeingDay
21%14%27%20%11%4
5749
Night
20%15%28%24%9%
15018

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
14%7%25%6%35%5%5%6%38%
1432
16th to endDay
13%7%35%5%35%46%7%37%
1644
February1st to 15thDay
15%8%46%6%35%45%7%33%
1603
16th to endDay
14%7%36%5%35%446%37%
1580
March1st to 15thDay
16%7%35%5%3436%8%35%
1823
16th to endDay
16%7%35%5%24445%39%
2211
April1st to 15thDay
18%8%24424346%39%
2152
16th to endDay
16%5%25%5%34446%42%
2160
May1st to 15thDay
21%6%35%5%34447%34%
2418
16th to endDay
16%5%35%5%25%5%5%8%34%
2618
June1st to 15thDay
19%426%5%345%5%8%32%
2520
16th to endDay
13%5%36%6%45%46%9%35%
2520
July1st to 15thDay
12%5%25%6%46%5%5%8%34%
2520
16th to endDay
9%5%26%6%36%5%7%9%37%
2654
August1st to 15thDay
13%5%16%6%46%5%7%7%34%
2318
16th to endDay
13%425%5%26%45%7%41%
2292
September1st to 15thDay
15%5%25%4345%5%6%43%
2160
16th to endDay
13%5%25%43435%7%44%
1934
October1st to 15thDay
17%7%35%423438%39%
1667
16th to endDay
20%6%135%3445%6%38%
1689
November1st to 15thDay
17%7%2432325%5%45%
1581
16th to endDay
18%6%233235%46%41%
1530
December1st to 15thDay
15%8%37%5%3445%5%36%
1440
16th to endDay
19%9%245%35%45%7%31%
1536
January1st to 15thNight
16%6%25%5%25%45%6%39%
2506
16th to endNight
13%8%25%5%3445%7%39%
2578
February1st to 15thNight
14%7%26%5%35%5%46%38%
2257
16th to endNight
14%6%35%42335%7%42%
1893
March1st to 15thNight
17%7%2432435%7%40%
2111
16th to endNight
16%6%35%42345%7%42%
2011
April1st to 15thNight
17%6%35%5%34448%36%
1796
16th to endNight
17%5%15%434446%42%
1800
May1st to 15thNight
17%7%345%3345%6%38%
1542
16th to endNight
15%5%15%43445%7%40%
1495
June1st to 15thNight
20%424325%448%40%
1440
16th to endNight
11%325%3245%5%8%47%
1440
July1st to 15thNight
11%4245%25%45%8%43%
1440
16th to endNight
11%214425%6%6%10%44%
1514
August1st to 15thNight
11%42333445%8%46%
1628
16th to endNight
13%3235%345%48%44%
1910
September1st to 15thNight
16%413423446%48%
1800
16th to endNight
12%424423436%50%
1884
October1st to 15thNight
19%5%24423335%45%
1961
16th to endNight
19%5%13313447%44%
2182
November1st to 15thNight
15%6%24323446%45%
2277
16th to endNight
16%6%25%42445%6%41%
2427
December1st to 15thNight
19%7%345%35%45%6%34%
2520
16th to endNight
18%7%245%35%45%7%35%
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
14%6%26%5%35%446%38%
1432
16th to endDay
13%6%45%5%3445%7%38%
1644
February1st to 15thDay
15%7%46%6%3445%7%34%
1603
16th to endDay
14%8%35%5%25%5%45%38%
1580
March1st to 15thDay
16%8%35%5%3345%8%34%
1833
16th to endDay
16%7%35%6%23345%40%
2210
April1st to 15thDay
19%7%34424346%40%
2152
16th to endDay
15%5%35%5%24346%42%
2160
May1st to 15thDay
20%6%25%5%25%447%33%
2418
16th to endDay
15%7%26%5%35%5%5%7%35%
2618
June1st to 15thDay
18%5%25%6%35%5%6%8%33%
2520
16th to endDay
12%6%27%5%35%5%5%8%35%
2520
July1st to 15thDay
12%6%26%6%45%5%6%8%34%
2520
16th to endDay
10%5%26%6%35%5%6%9%37%
2654
August1st to 15thDay
12%5%26%6%36%5%7%7%34%
2318
16th to endDay
14%425%4345%5%8%41%
2292
September1st to 15thDay
15%425%5%26%446%43%
2160
16th to endDay
13%5%245%335%46%44%
1934
October1st to 15thDay
18%6%25%423446%40%
1667
16th to endDay
20%5%24434446%39%
1689
November1st to 15thDay
17%8%24312346%44%
1581
16th to endDay
17%6%1442445%6%41%
1530
December1st to 15thDay
16%7%37%5%2445%5%36%
1440
16th to endDay
19%9%35%5%35%447%32%
1536
January1st to 15thNight
16%6%25%425%45%7%39%
2506
16th to endNight
14%7%36%42445%7%39%
2578
February1st to 15thNight
13%7%35%6%35%45%6%38%
2250
16th to endNight
15%5%25%424447%42%
1893
March1st to 15thNight
17%6%25%42335%7%40%
2124
16th to endNight
16%6%35%41445%5%42%
2011
April1st to 15thNight
17%6%26%5%25%448%36%
1796
16th to endNight
16%6%2442445%6%42%
1800
May1st to 15thNight
17%6%35%42445%6%38%
1542
16th to endNight
14%6%245%25%46%8%40%
1495
June1st to 15thNight
19%42432445%8%39%
1440
16th to endNight
10%224435%5%5%8%46%
1440
July1st to 15thNight
11%4245%35%5%6%8%43%
1440
16th to endNight
10%314427%5%6%10%43%
1514
August1st to 15thNight
11%42443445%8%46%
1628
16th to endNight
13%3145%3346%7%45%
1910
September1st to 15thNight
15%423423445%48%
1800
16th to endNight
12%425%433345%50%
1884
October1st to 15thNight
18%6%24424335%44%
1961
16th to endNight
18%6%14313346%44%
2182
November1st to 15thNight
15%7%24313346%45%
2277
16th to endNight
17%5%35%42445%6%41%
2427
December1st to 15thNight
19%6%345%35%45%6%34%
2520
16th to endNight
18%8%25%5%35%446%36%
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
46%412%23%10%2
1433
16th to endDay
44%5%11%23%12%2
1644
February1st to 15thDay
50%5%11%19%12%1
1606
16th to endDay
46%5%10%23%12%1
1580
March1st to 15thDay
46%5%14%21%10%2
1833
16th to endDay
46%5%8%19%16%2
2211
April1st to 15thDay
45%49%22%13%3
2152
16th to endDay
43%49%20%19%3
2160
May1st to 15thDay
50%5%9%19%13%2
2418
16th to endDay
46%7%12%18%13%1
2622
June1st to 15thDay
47%8%12%20%10%
2520
16th to endDay
44%7%12%22%11%
2520
July1st to 15thDay
45%6%11%19%15%1
2371
16th to endDay
40%8%13%22%11%2
2487
August1st to 15thDay
44%7%13%19%14%
2304
16th to endDay
39%6%10%24%17%1
2292
September1st to 15thDay
41%6%11%19%20%1
2160
16th to endDay
39%48%21%22%3
1934
October1st to 15thDay
43%6%11%19%16%2
1667
16th to endDay
44%5%10%23%14%1
1689
November1st to 15thDay
41%313%20%17%3
1581
16th to endDay
42%5%10%25%14%2
1530
December1st to 15thDay
47%6%15%18%10%1
1440
16th to endDay
50%6%13%18%10%
1536
January1st to 15thNight
43%5%13%20%12%2
2506
16th to endNight
43%5%11%25%12%1
2578
February1st to 15thNight
46%414%19%12%1
2258
16th to endNight
41%5%8%25%17%1
1893
March1st to 15thNight
43%5%13%22%12%2
2124
16th to endNight
41%312%21%17%2
2011
April1st to 15thNight
47%410%19%15%1
1796
16th to endNight
42%5%9%20%20%2
1800
May1st to 15thNight
45%6%10%20%15%1
1542
16th to endNight
40%8%15%20%12%2
1497
June1st to 15thNight
43%6%13%22%13%
1440
16th to endNight
34%6%16%28%13%
1440
July1st to 15thNight
36%10%13%23%14%2
1360
16th to endNight
32%9%18%22%14%2
1418
August1st to 15thNight
35%6%14%26%16%1
1618
16th to endNight
36%7%12%21%20%1
1910
September1st to 15thNight
37%5%11%25%19%
1800
16th to endNight
35%48%22%26%1
1884
October1st to 15thNight
42%5%10%22%17%1
1961
16th to endNight
39%5%15%25%14%
2182
November1st to 15thNight
40%412%21%18%3
2277
16th to endNight
43%413%24%12%1
2427
December1st to 15thNight
48%6%14%19%10%
2520
16th to endNight
48%5%13%21%10%
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
31%31%20%13%3
60
16th to endDay
30%23%37%7%1
82
February1st to 15thDay
27%37%24%10%
120
16th to endDay
25%23%33%15%2
239
March1st to 15thDay
24%25%26%18%4
270
16th to endDay
21%23%34%10%6%2
288
April1st to 15thDay
27%19%28%17%7%
270
16th to endDay
21%17%30%16%11%3
270
May1st to 15thDay
35%15%22%14%9%2
288
16th to endDay
18%12%30%25%9%3
331
June1st to 15thDay
20%15%23%24%13%1
315
16th to endDay
18%12%30%25%11%1
315
July1st to 15thDay
17%8%27%28%14%3
305
16th to endDay
13%7%25%27%20%4
326
August1st to 15thDay
13%7%28%26%16%8%
313
16th to endDay
14%325%23%21%10%
332
September1st to 15thDay
16%10%28%21%13%9%
315
16th to endDay
18%227%20%15%15%
287
October1st to 15thDay
23%7%23%24%15%5%
255
16th to endDay
23%18%27%20%8%
259
November1st to 15thDay
22%18%22%22%11%2
235
16th to endDay
24%21%28%18%6%1
150
December1st to 15thDay
25%26%30%11%6%
60
16th to endDay
37%25%28%7%1
64
January1st to 15thNight
22%20%33%19%3
720
16th to endNight
22%22%34%17%1
768
February1st to 15thNight
21%23%37%17%
704
16th to endNight
25%23%31%17%1
631
March1st to 15thNight
27%23%28%17%3
720
16th to endNight
23%22%30%16%5%
768
April1st to 15thNight
23%20%33%18%3
718
16th to endNight
22%14%32%22%7%
720
May1st to 15thNight
22%11%32%25%7%
462
16th to endNight
17%7%31%32%10%
375
June1st to 15thNight
21%6%21%33%15%
360
16th to endNight
11%427%45%10%
360
July1st to 15thNight
12%325%41%16%
340
16th to endNight
10%223%42%19%1
376
August1st to 15thNight
12%223%37%21%2
547
16th to endNight
14%318%35%24%2
764
September1st to 15thNight
16%7%26%31%15%2
720
16th to endNight
14%6%22%27%24%5%
693
October1st to 15thNight
23%9%24%28%13%
660
16th to endNight
24%15%30%23%5%
704
November1st to 15thNight
21%16%25%24%9%1
700
16th to endNight
21%20%26%22%8%1
720
December1st to 15thNight
25%19%30%18%5%
720
16th to endNight
25%22%31%18%2
768
Page generated at 2017-09-25 09:02:28. Version ac04

Copyright 2017 A. Danko


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