North Sterling State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Sterling State Park clear sky chart from 2005-11-05 to 2018-10-08.

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
50%
17386
25%
51001
16%
17345
57%
17345
37%
29190

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
45%
975
26%
2716
16%
970
54%
970
40%
1519
January16th to endNight
40%
985
30%
2857
17%
985
53%
985
40%
1582
February1st to 15thNight
38%
756
21%
2378
10%
756
50%
756
31%
1425
February16th to endNight
38%
684
26%
2050
14%
684
49%
684
34%
1186
March1st to 15thNight
46%
780
27%
2340
16%
780
55%
780
39%
1302
March16th to endNight
38%
676
22%
2175
14%
676
47%
676
31%
1249
April1st to 15thNight
38%
584
19%
1948
13%
584
49%
584
27%
1171
April16th to endNight
36%
579
18%
1880
13%
579
44%
579
24%
1183
May1st to 15thNight
46%
585
19%
1755
15%
585
51%
585
28%
1122
May16th to endNight
46%
609
15%
1627
10%
609
50%
609
28%
1086
June1st to 15thNight
52%
585
15%
1560
7%
585
56%
585
37%
959
June16th to endNight
60%
585
21%
1560
14%
585
62%
585
45%
885
July1st to 15thNight
64%
555
20%
1480
12%
555
68%
555
37%
903
July16th to endNight
74%
612
25%
1544
21%
579
74%
579
45%
872
August1st to 15thNight
65%
575
18%
1730
17%
572
67%
572
33%
1040
August16th to endNight
69%
621
26%
2070
29%
621
73%
621
43%
1027
September1st to 15thNight
61%
585
28%
1953
27%
585
69%
585
39%
1038
September16th to endNight
63%
582
33%
2145
32%
582
71%
582
43%
986
October1st to 15thNight
50%
654
29%
2158
21%
654
57%
654
33%
1193
October16th to endNight
56%
879
35%
2415
20%
879
64%
879
47%
1278
November1st to 15thNight
53%
950
30%
2470
16%
950
59%
950
46%
1368
November16th to endNight
52%
975
34%
2548
17%
975
62%
975
46%
1446
December1st to 15thNight
40%
975
21%
2730
10%
975
49%
975
37%
1605
December16th to endNight
42%
1040
27%
2912
14%
1040
53%
1040
34%
1765

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
7%41332445%7%54%
52156
Night
6%5%2442445%7%53%
51173
Cloud CoverDay
7%41332445%7%54%
52154
Night
6%5%2442445%7%53%
51173
TransparencyDay
27%5%12%27%19%6%
51830
Night
29%5%13%26%19%5%
51001
SeeingDay
10%5%24%32%21%5%
7351
Night
9%5%29%43%12%
17396

By Month

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
35%2343345%6%57%
1552
16th to endDay
442333345%7%56%
1730
February1st to 15thDay
5%7%36%425%45%8%47%
1812
16th to endDay
35%25%42445%7%52%
1710
March1st to 15thDay
5%413334447%57%
1950
16th to endDay
8%6%244345%5%8%47%
2398
April1st to 15thDay
11%5%2432445%6%50%
2330
16th to endDay
13%6%2442345%7%43%
2353
May1st to 15thDay
12%5%2442445%7%46%
2526
16th to endDay
10%4234245%6%9%46%
2837
June1st to 15thDay
7%212315%5%6%8%53%
2730
16th to endDay
221222345%9%62%
2730
July1st to 15thDay
5%313325%5%5%9%54%
2730
16th to endDay
3213335%6%6%10%54%
2880
August1st to 15thDay
42144345%7%9%51%
2471
16th to endDay
5%212323348%61%
2484
September1st to 15thDay
8%212323446%58%
2337
16th to endDay
7%313212345%64%
2145
October1st to 15thDay
12%412313445%55%
1970
16th to endDay
7%313322335%62%
1797
November1st to 15thDay
35%13324446%60%
1718
16th to endDay
3423323446%62%
1742
December1st to 15thDay
5%6%26%423346%53%
1560
16th to endDay
6%7%24324447%51%
1664
January1st to 15thNight
35%3441335%7%56%
2716
16th to endNight
45%24423446%57%
2857
February1st to 15thNight
5%6%35%5%3445%7%47%
2368
16th to endNight
37%36%423446%53%
2050
March1st to 15thNight
45%24414446%56%
2340
16th to endNight
8%7%2442445%7%49%
2175
April1st to 15thNight
11%7%24423445%48%
1948
16th to endNight
16%7%15%423347%43%
1880
May1st to 15thNight
13%4244346%5%8%41%
1754
16th to endNight
13%5%1443445%8%42%
1626
June1st to 15thNight
6%313335%5%6%9%50%
1560
16th to endNight
3213415%5%6%9%55%
1560
July1st to 15thNight
6%4235%36%5%6%10%47%
1560
16th to endNight
411342446%11%54%
1640
August1st to 15thNight
5%3245%46%5%7%10%45%
1738
16th to endNight
5%31332345%7%58%
2070
September1st to 15thNight
7%31342446%7%54%
1953
16th to endNight
5%312313346%64%
2145
October1st to 15thNight
13%5%13323235%55%
2158
16th to endNight
6%313322346%63%
2415
November1st to 15thNight
431331345%6%59%
2470
16th to endNight
3413324345%60%
2548
December1st to 15thNight
5%6%33334446%53%
2730
16th to endNight
5%7%2442445%7%51%
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
35%24333446%57%
1552
16th to endDay
442332345%7%56%
1730
February1st to 15thDay
5%7%46%425%35%7%48%
1812
16th to endDay
35%35%42445%7%53%
1710
March1st to 15thDay
5%413334447%57%
1950
16th to endDay
8%6%2443445%7%47%
2396
April1st to 15thDay
11%6%2332345%6%49%
2330
16th to endDay
13%7%25%42435%8%43%
2353
May1st to 15thDay
12%5%2432445%6%46%
2526
16th to endDay
10%42342446%9%46%
2837
June1st to 15thDay
7%2123145%6%9%53%
2730
16th to endDay
22221346%9%63%
2730
July1st to 15thDay
5%313325%5%5%9%54%
2730
16th to endDay
3213335%6%6%10%54%
2880
August1st to 15thDay
42144345%7%10%51%
2471
16th to endDay
6%212323348%60%
2484
September1st to 15thDay
9%212323446%58%
2337
16th to endDay
7%313212345%64%
2145
October1st to 15thDay
12%422323445%55%
1970
16th to endDay
7%313312335%62%
1797
November1st to 15thDay
35%1332435%6%59%
1718
16th to endDay
3323323336%62%
1742
December1st to 15thDay
5%6%35%423346%54%
1560
16th to endDay
6%7%24324447%51%
1664
January1st to 15thNight
35%3441335%7%56%
2716
16th to endNight
45%25%423447%56%
2857
February1st to 15thNight
5%7%35%5%3445%7%47%
2368
16th to endNight
36%35%5%2435%6%53%
2050
March1st to 15thNight
45%24424446%56%
2340
16th to endNight
8%7%2442445%6%49%
2175
April1st to 15thNight
11%7%24423445%48%
1948
16th to endNight
16%7%25%423346%43%
1880
May1st to 15thNight
13%4144346%6%8%41%
1754
16th to endNight
13%5%15%4345%5%8%42%
1626
June1st to 15thNight
6%413335%5%6%9%50%
1560
16th to endNight
3213325%47%9%55%
1560
July1st to 15thNight
6%3235%36%5%5%10%47%
1560
16th to endNight
412432447%10%55%
1640
August1st to 15thNight
5%4145%36%5%7%9%45%
1738
16th to endNight
5%21232346%7%58%
2070
September1st to 15thNight
6%31342346%7%54%
1953
16th to endNight
6%312313346%64%
2145
October1st to 15thNight
13%413313335%55%
2158
16th to endNight
6%312322336%63%
2415
November1st to 15thNight
441331345%7%59%
2470
16th to endNight
3423324345%61%
2548
December1st to 15thNight
5%6%33334446%53%
2730
16th to endNight
5%7%2442445%7%51%
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
27%5%15%33%15%2
1553
16th to endDay
25%417%32%17%2
1730
February1st to 15thDay
35%5%15%31%9%2
1813
16th to endDay
29%411%30%19%4
1710
March1st to 15thDay
25%414%25%24%5%
1950
16th to endDay
34%6%13%25%15%3
2398
April1st to 15thDay
33%5%11%28%15%5%
2330
16th to endDay
37%414%23%15%3
2353
May1st to 15thDay
37%5%12%29%13%1
2526
16th to endDay
32%7%17%25%13%3
2841
June1st to 15thDay
24%6%16%26%18%7%
2730
16th to endDay
17%5%11%29%26%9%
2730
July1st to 15thDay
25%6%10%23%22%11%
2581
16th to endDay
22%7%13%28%20%7%
2713
August1st to 15thDay
25%8%14%27%15%8%
2455
16th to endDay
21%49%26%27%10%
2484
September1st to 15thDay
24%5%9%24%21%15%
2337
16th to endDay
21%37%25%33%8%
2145
October1st to 15thDay
31%5%9%23%23%7%
1970
16th to endDay
23%310%29%22%10%
1797
November1st to 15thDay
24%313%26%22%8%
1718
16th to endDay
23%39%30%27%5%
1742
December1st to 15thDay
31%411%34%14%3
1560
16th to endDay
32%5%14%29%14%2
1664
January1st to 15thNight
27%415%29%20%2
2716
16th to endNight
28%411%31%21%4
2857
February1st to 15thNight
34%6%16%28%11%3
2378
16th to endNight
31%412%27%18%5%
2050
March1st to 15thNight
28%39%26%24%6%
2340
16th to endNight
33%5%14%24%18%3
2175
April1st to 15thNight
37%5%13%24%15%3
1948
16th to endNight
41%5%10%23%16%2
1880
May1st to 15thNight
38%6%14%26%11%1
1755
16th to endNight
38%8%18%19%9%5%
1627
June1st to 15thNight
28%9%19%23%12%5%
1560
16th to endNight
23%7%15%27%19%6%
1560
July1st to 15thNight
30%7%12%24%17%8%
1480
16th to endNight
23%6%15%29%18%5%
1544
August1st to 15thNight
31%8%18%21%13%6%
1730
16th to endNight
22%5%12%25%24%9%
2070
September1st to 15thNight
26%5%12%23%20%11%
1953
16th to endNight
21%38%32%24%9%
2145
October1st to 15thNight
31%411%23%21%8%
2158
16th to endNight
23%310%27%24%10%
2415
November1st to 15thNight
23%411%25%24%9%
2470
16th to endNight
25%310%28%24%7%
2548
December1st to 15thNight
31%415%29%15%3
2730
16th to endNight
33%5%14%29%16%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
5%5%25%42%14%5%
135
16th to endDay
9%8%33%35%12%
144
February1st to 15thDay
14%6%40%34%4
135
16th to endDay
9%5%46%24%12%1
120
March1st to 15thDay
5%10%33%33%15%2
135
16th to endDay
14%12%33%27%12%
306
April1st to 15thDay
14%17%34%21%9%2
329
16th to endDay
20%16%25%23%11%2
365
May1st to 15thDay
16%8%24%29%18%3
543
16th to endDay
16%6%24%27%20%4
597
June1st to 15thDay
8%422%32%21%9%
570
16th to endDay
4325%37%25%3
570
July1st to 15thDay
9%15%36%30%8%
550
16th to endDay
3113%38%34%7%
595
August1st to 15thDay
6%216%35%32%5%
459
16th to endDay
6%223%32%25%9%
396
September1st to 15thDay
6%222%32%21%13%
372
16th to endDay
15%219%30%25%6%
180
October1st to 15thDay
19%322%29%17%7%
157
16th to endDay
11%7%25%28%19%7%
144
November1st to 15thDay
5%221%35%23%11%
135
16th to endDay
10%9%31%40%6%1
135
December1st to 15thDay
8%12%37%31%8%
135
16th to endDay
13%5%36%34%8%
144
January1st to 15thNight
5%7%35%40%10%
975
16th to endNight
7%6%40%37%7%
985
February1st to 15thNight
8%5%39%40%6%
764
16th to endNight
7%7%39%40%5%
684
March1st to 15thNight
6%5%36%41%9%
780
16th to endNight
12%7%36%35%7%
676
April1st to 15thNight
15%8%34%37%4
584
16th to endNight
19%8%30%31%9%
579
May1st to 15thNight
16%5%27%39%11%
585
16th to endNight
15%428%35%15%
611
June1st to 15thNight
7%431%40%15%
585
16th to endNight
4327%51%13%
585
July1st to 15thNight
6%217%50%22%
555
16th to endNight
4112%54%26%
612
August1st to 15thNight
6%15%54%21%
575
16th to endNight
6%17%56%19%
621
September1st to 15thNight
7%222%47%18%1
585
16th to endNight
6%321%48%19%
582
October1st to 15thNight
17%6%22%38%13%1
654
16th to endNight
9%425%44%15%
879
November1st to 15thNight
7%5%28%46%11%
950
16th to endNight
7%5%30%44%11%
975
December1st to 15thNight
8%6%39%39%6%
975
16th to endNight
9%6%34%43%6%
1040
Page generated at 2018-10-09 08:39:11. Version ac04

Copyright 2018 A. Danko


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