Sesquicentennial State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sesquicentennial State Park clear sky chart from 2005-11-05 to 2019-06-02.

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
51%
18140
22%
53802
16%
18099
58%
18099
29%
33657

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
34%
838
23%
2717
11%
836
48%
836
26%
1632
January16th to endNight
34%
896
25%
2912
16%
896
47%
896
25%
1753
February1st to 15thNight
35%
824
23%
2607
14%
821
48%
821
26%
1596
February16th to endNight
32%
735
26%
2156
14%
735
45%
735
29%
1340
March1st to 15thNight
37%
840
26%
2310
14%
840
47%
840
31%
1440
March16th to endNight
40%
896
21%
2464
12%
896
47%
896
31%
1552
April1st to 15thNight
45%
838
24%
2247
13%
838
52%
838
35%
1370
April16th to endNight
48%
769
26%
2015
14%
769
55%
769
37%
1215
May1st to 15thNight
54%
629
20%
1890
12%
629
59%
629
30%
1162
May16th to endNight
64%
657
19%
1971
14%
657
66%
657
29%
1247
June1st to 15thNight
66%
588
15%
1765
13%
588
67%
588
26%
1166
June16th to endNight
71%
585
14%
1755
12%
585
71%
585
27%
1161
July1st to 15thNight
70%
555
12%
1665
10%
555
70%
555
25%
1110
July16th to endNight
73%
612
11%
1739
9%
579
74%
579
25%
1193
August1st to 15thNight
68%
575
14%
1715
13%
572
68%
572
24%
1194
August16th to endNight
65%
738
14%
1980
11%
738
66%
738
27%
1371
September1st to 15thNight
68%
780
19%
2136
17%
780
69%
780
28%
1430
September16th to endNight
58%
777
19%
2145
16%
777
61%
777
26%
1464
October1st to 15thNight
55%
780
29%
2287
27%
780
61%
780
34%
1353
October16th to endNight
55%
832
34%
2496
27%
832
66%
832
38%
1375
November1st to 15thNight
52%
820
29%
2461
24%
820
61%
820
35%
1411
November16th to endNight
49%
840
28%
2727
23%
840
58%
840
31%
1554
December1st to 15thNight
43%
840
24%
2730
18%
840
54%
840
25%
1702
December16th to endNight
39%
896
22%
2912
17%
896
47%
896
23%
1866

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
12%5%25%5%345%5%7%43%
54524
Night
12%5%2442445%7%44%
54002
TransparencyDay
38%6%11%20%17%5%
54225
Night
37%6%11%19%18%6%
53805
SeeingDay
14%5%19%24%23%13%
7925
Night
14%5%21%33%22%3
18145

By Month

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
16%6%25%333445%45%
1881
16th to endDay
16%5%23423435%48%
2016
February1st to 15thDay
17%5%15%423346%44%
1910
16th to endDay
19%5%25%323245%45%
1888
March1st to 15thDay
14%424424345%49%
2310
16th to endDay
14%425%5%3435%7%44%
2463
April1st to 15thDay
10%4244235%6%7%48%
2360
16th to endDay
9%4234245%5%8%49%
2561
May1st to 15thDay
9%5%25%5%3445%7%45%
2721
16th to endDay
10%6%25%6%35%5%5%7%39%
2847
June1st to 15thDay
9%415%5%35%5%7%11%39%
2548
16th to endDay
5%325%5%36%7%8%11%40%
2535
July1st to 15thDay
8%425%7%46%7%8%10%34%
2535
16th to endDay
7%327%6%37%8%9%11%32%
2673
August1st to 15thDay
11%5%26%6%46%8%7%10%31%
2487
16th to endDay
12%5%25%6%46%7%7%10%30%
2558
September1st to 15thDay
9%425%6%35%5%7%9%41%
2151
16th to endDay
15%5%25%435%45%7%39%
2145
October1st to 15thDay
14%414323346%50%
2002
16th to endDay
10%42432332459%
2080
November1st to 15thDay
14%5%13323235%53%
2057
16th to endDay
12%6%24423335%51%
1890
December1st to 15thDay
17%7%25%5%24346%40%
1890
16th to endDay
20%6%14424346%41%
2016
January1st to 15thNight
14%6%25%323445%47%
2717
16th to endNight
16%5%24323335%48%
2912
February1st to 15thNight
16%5%2442335%6%45%
2600
16th to endNight
15%5%25%323445%46%
2156
March1st to 15thNight
13%5%23424346%48%
2310
16th to endNight
12%425%42345%6%46%
2464
April1st to 15thNight
10%424423447%51%
2247
16th to endNight
10%323323447%51%
2015
May1st to 15thNight
8%5%25%445%5%6%8%44%
1889
16th to endNight
9%415%5%36%5%6%9%42%
1970
June1st to 15thNight
10%425%5%46%6%9%10%34%
1765
16th to endNight
4425%5%47%6%9%11%37%
1755
July1st to 15thNight
7%427%6%46%7%9%9%34%
1755
16th to endNight
5%5%26%6%47%7%9%12%34%
1847
August1st to 15thNight
9%5%26%6%37%6%9%10%32%
1726
16th to endNight
10%5%25%5%45%6%7%12%33%
1980
September1st to 15thNight
8%425%6%45%5%7%10%38%
2136
16th to endNight
15%5%25%5%34446%41%
2145
October1st to 15thNight
15%5%13312336%52%
2287
16th to endNight
10%42332345%5%56%
2496
November1st to 15thNight
14%5%23213236%54%
2461
16th to endNight
12%5%2332345%6%50%
2727
December1st to 15thNight
18%5%24423445%45%
2730
16th to endNight
18%6%25%424346%40%
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
41%39%17%22%6%
1882
16th to endDay
38%36%18%24%8%
2016
February1st to 15thDay
41%38%19%22%5%
1912
16th to endDay
42%35%21%21%6%
1888
March1st to 15thDay
37%48%20%20%9%
2310
16th to endDay
39%410%20%19%4
2464
April1st to 15thDay
33%5%11%22%21%5%
2360
16th to endDay
32%5%11%21%22%7%
2561
May1st to 15thDay
36%5%14%20%19%2
2721
16th to endDay
40%7%12%23%13%1
2851
June1st to 15thDay
36%8%17%25%10%1
2548
16th to endDay
33%9%17%25%12%2
2535
July1st to 15thDay
38%11%17%19%9%2
2396
16th to endDay
38%13%19%18%7%1
2518
August1st to 15thDay
43%10%15%17%10%1
2474
16th to endDay
44%9%18%17%8%1
2558
September1st to 15thDay
37%8%14%18%17%3
2151
16th to endDay
43%7%9%18%16%4
2145
October1st to 15thDay
35%48%22%22%6%
2002
16th to endDay
29%26%20%29%11%
2080
November1st to 15thDay
34%27%19%26%10%
2057
16th to endDay
35%39%18%23%10%
1890
December1st to 15thDay
45%37%19%17%6%
1890
16th to endDay
44%38%21%16%6%
2016
January1st to 15thNight
38%39%15%24%7%
2717
16th to endNight
39%35%19%22%10%
2912
February1st to 15thNight
39%37%20%20%8%
2609
16th to endNight
38%38%21%20%7%
2156
March1st to 15thNight
37%49%17%21%9%
2310
16th to endNight
36%5%11%19%21%5%
2464
April1st to 15thNight
33%411%22%21%7%
2247
16th to endNight
31%410%21%21%9%
2015
May1st to 15thNight
35%7%14%21%18%3
1890
16th to endNight
36%8%12%25%14%2
1972
June1st to 15thNight
38%9%18%21%10%
1765
16th to endNight
35%12%18%20%10%2
1755
July1st to 15thNight
38%11%20%17%9%3
1665
16th to endNight
37%13%22%15%8%1
1739
August1st to 15thNight
40%12%19%17%8%1
1715
16th to endNight
40%10%21%17%9%
1980
September1st to 15thNight
38%9%14%17%14%4
2136
16th to endNight
44%5%11%17%16%3
2145
October1st to 15thNight
34%310%20%23%7%
2287
16th to endNight
29%37%19%26%14%
2496
November1st to 15thNight
32%37%16%26%12%
2461
16th to endNight
33%47%18%24%12%
2727
December1st to 15thNight
41%49%19%18%7%
2730
16th to endNight
44%39%19%16%6%
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
18%13%37%21%8%
180
16th to endDay
17%17%35%23%5%
192
February1st to 15thDay
21%16%37%20%4
180
16th to endDay
25%8%34%24%6%
207
March1st to 15thDay
15%14%33%27%7%
390
16th to endDay
13%8%37%24%14%1
416
April1st to 15thDay
16%8%26%24%20%3
390
16th to endDay
11%6%23%27%21%10%
379
May1st to 15thDay
10%6%22%27%24%9%
408
16th to endDay
15%310%21%27%21%
459
June1st to 15thDay
10%8%20%37%21%
379
16th to endDay
8%10%23%30%25%
375
July1st to 15thDay
8%1425%30%28%
365
16th to endDay
8%16%24%34%24%
390
August1st to 15thDay
17%15%18%31%25%
358
16th to endDay
13%7%19%30%28%
396
September1st to 15thDay
14%18%19%32%22%
375
16th to endDay
18%10%25%29%14%
374
October1st to 15thDay
17%114%30%23%13%
375
16th to endDay
8%6%21%30%24%9%
400
November1st to 15thDay
21%420%28%20%5%
385
16th to endDay
6%10%25%35%21%2
180
December1st to 15thDay
27%7%34%20%10%1
180
16th to endDay
25%9%35%19%9%
192
January1st to 15thNight
18%9%32%30%9%
840
16th to endNight
19%8%32%35%4
896
February1st to 15thNight
18%11%29%34%4
824
16th to endNight
18%8%34%33%5%
735
March1st to 15thNight
15%8%33%36%6%
840
16th to endNight
14%7%32%33%11%
896
April1st to 15thNight
12%9%29%35%12%
838
16th to endNight
12%6%27%34%17%
769
May1st to 15thNight
11%324%39%20%1
630
16th to endNight
10%113%35%33%4
659
June1st to 15thNight
12%19%35%32%7%
588
16th to endNight
6%18%35%37%10%
585
July1st to 15thNight
8%6%35%40%8%
555
16th to endNight
8%5%30%48%6%
612
August1st to 15thNight
13%426%47%7%
575
16th to endNight
12%6%27%42%9%
738
September1st to 15thNight
10%16%28%45%7%
780
16th to endNight
18%110%30%33%4
777
October1st to 15thNight
16%317%29%27%5%
780
16th to endNight
11%5%22%31%26%2
832
November1st to 15thNight
16%422%35%18%3
820
16th to endNight
14%7%23%33%18%1
840
December1st to 15thNight
20%5%23%36%12%1
840
16th to endNight
20%7%26%35%9%
896
Page generated at 2019-06-02 19:43:09. Version ac04

Copyright 2019 A. Danko


Sesquicentennial State Park Clear Sky Chart |Charts Home