Pleasant Grove Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pleasant Grove Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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
46%
24016
22%
74405
14%
23958
54%
23958
25%
46576

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 10thNight
24%
760
23%
2459
9%
757
41%
757
19%
1538
January11th to 20thNight
30%
737
24%
2393
12%
737
45%
737
20%
1495
January21st to endNight
24%
792
27%
2574
10%
792
45%
792
22%
1543
February1st to 10thNight
32%
720
25%
2180
12%
720
46%
720
24%
1365
February11th to 20thNight
23%
703
22%
2098
7%
699
38%
699
21%
1355
February21st to endNight
25%
592
23%
1776
10%
592
38%
592
22%
1164
March1st to 10thNight
33%
720
26%
2044
14%
720
43%
720
30%
1254
March11th to 20thNight
30%
720
21%
1980
9%
720
40%
720
26%
1294
March21st to endNight
34%
792
21%
2178
9%
792
44%
792
26%
1416
April1st to 10thNight
38%
720
25%
1980
13%
720
48%
720
31%
1197
April11th to 20thNight
41%
605
26%
1807
14%
605
53%
605
32%
1046
April21st to endNight
47%
540
29%
1620
18%
540
56%
540
34%
939
May1st to 10thNight
49%
540
21%
1620
11%
540
57%
540
32%
960
May11th to 20thNight
51%
531
14%
1593
8%
531
54%
531
25%
1051
May21st to endNight
60%
582
19%
1744
14%
582
63%
582
27%
1130
June1st to 10thNight
63%
540
16%
1620
13%
540
65%
540
26%
1051
June11th to 20thNight
67%
540
16%
1620
13%
540
69%
540
32%
1001
June21st to endNight
67%
540
14%
1620
12%
540
68%
540
27%
1051
July1st to 10thNight
64%
525
10%
1575
9%
525
64%
525
21%
1122
July11th to 20thNight
70%
522
11%
1566
9%
522
70%
522
22%
1096
July21st to endNight
69%
591
14%
1672
12%
558
70%
558
25%
1123
August1st to 10thNight
65%
537
11%
1600
11%
534
65%
534
20%
1138
August11th to 20thNight
63%
534
18%
1606
18%
534
64%
534
22%
1119
August21st to endNight
61%
631
14%
2017
13%
631
62%
631
19%
1420
September1st to 10thNight
65%
720
18%
1980
16%
720
66%
720
28%
1318
September11th to 20thNight
58%
720
20%
1980
16%
720
61%
720
27%
1333
September21st to endNight
58%
720
25%
1980
19%
720
64%
720
33%
1247
October1st to 10thNight
57%
720
27%
1980
21%
720
63%
720
36%
1185
October11th to 20thNight
51%
720
30%
2149
23%
720
61%
720
33%
1263
October21st to endNight
52%
792
33%
2376
25%
792
64%
792
37%
1307
November1st to 10thNight
51%
740
29%
2299
24%
740
60%
740
34%
1276
November11th to 20thNight
40%
760
28%
2470
19%
760
54%
760
31%
1401
November21st to endNight
41%
760
26%
2470
18%
760
54%
760
27%
1469
December1st to 10thNight
33%
760
25%
2470
13%
760
47%
760
19%
1584
December11th to 20thNight
35%
759
29%
2896
17%
758
49%
758
22%
1634
December21st to endNight
28%
831
14%
4413
11%
817
40%
817
11%
2691

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
14%5%25%5%35%5%6%8%43%
74907
Night
14%5%25%5%345%5%7%45%
74878
TransparencyDay
38%8%12%19%18%5%
74630
Night
38%7%11%19%20%6%
74674
SeeingDay
17%9%22%24%19%9%
13913
Night
16%9%22%29%20%3
24024

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 10thDay
17%5%25%5%34346%46%
1706
11th to 20thDay
18%5%35%5%2445%5%45%
1656
21st to endDay
19%6%2442335%5%48%
1782
February1st to 10thDay
16%6%36%5%35%5%5%6%41%
1778
11th to 20thDay
22%5%34423445%44%
1748
21st to endDay
21%6%25%434346%41%
1480
March1st to 10thDay
15%5%2441335%6%51%
1916
11th to 20thDay
17%6%25%6%44446%42%
1980
21st to endDay
16%6%35%5%3445%7%42%
2178
April1st to 10thDay
12%425%5%3446%7%47%
1980
11th to 20thDay
12%5%26%5%35%447%48%
2114
21st to endDay
10%4244245%5%8%52%
2340
May1st to 10thDay
10%4245%35%5%5%8%49%
2340
11th to 20thDay
13%5%25%5%445%7%9%41%
2301
21st to endDay
12%5%246%36%5%6%10%41%
2531
June1st to 10thDay
9%5%36%7%46%6%8%12%34%
2340
11th to 20thDay
6%425%6%5%7%7%8%11%41%
2340
21st to endDay
7%415%6%48%8%9%11%39%
2340
July1st to 10thDay
9%6%36%7%47%7%8%10%32%
2340
11th to 20thDay
9%5%37%6%46%8%9%12%33%
2340
21st to endDay
7%5%35%7%5%7%7%8%14%33%
2547
August1st to 10thDay
9%6%28%7%48%8%8%10%30%
2327
11th to 20thDay
14%5%26%7%47%6%7%10%31%
2290
21st to endDay
13%7%37%7%36%6%7%8%32%
2319
September1st to 10thDay
11%425%7%46%7%7%9%39%
1980
11th to 20thDay
15%6%25%5%345%6%7%42%
1980
21st to endDay
17%5%2342445%7%46%
1980
October1st to 10thDay
15%424313346%55%
1980
11th to 20thDay
13%5%24322345%57%
1810
21st to endDay
12%425%423345%57%
1980
November1st to 10thDay
14%424423335%57%
1777
11th to 20thDay
14%5%24333446%54%
1710
21st to endDay
15%5%24424447%49%
1710
December1st to 10thDay
21%8%25%43445%6%39%
1710
11th to 20thDay
18%5%24433345%49%
2153
21st to endDay
23%6%2432345%6%42%
3124
January1st to 10thNight
19%5%25%43433447%
2459
11th to 20thNight
17%6%25%32445%6%44%
2393
21st to endNight
17%6%34423345%49%
2574
February1st to 10thNight
17%5%24434445%47%
2180
11th to 20thNight
21%6%24424345%44%
2098
21st to endNight
19%6%245%34446%44%
1776
March1st to 10thNight
14%5%25%42345%5%50%
2044
11th to 20thNight
17%424435%46%7%43%
1980
21st to endNight
14%5%36%43446%7%45%
2178
April1st to 10thNight
13%42343445%6%51%
1980
11th to 20thNight
13%42442335%7%52%
1807
21st to endNight
11%4244335%5%7%53%
1620
May1st to 10thNight
9%5%245%3445%8%51%
1620
11th to 20thNight
12%5%26%5%5%5%5%6%8%41%
1592
21st to endNight
11%5%25%5%5%5%5%6%9%41%
1744
June1st to 10thNight
9%6%25%6%46%7%7%12%36%
1620
11th to 20thNight
6%5%25%5%35%5%8%13%43%
1620
21st to endNight
8%425%6%35%7%10%12%38%
1620
July1st to 10thNight
10%6%37%6%46%7%7%11%32%
1620
11th to 20thNight
7%5%26%6%46%9%8%14%32%
1620
21st to endNight
6%427%7%47%7%9%15%31%
1771
August1st to 10thNight
11%6%26%6%5%7%8%9%10%30%
1611
11th to 20thNight
12%5%25%7%46%6%8%11%34%
1606
21st to endNight
11%7%37%6%5%6%7%8%9%31%
2017
September1st to 10thNight
10%5%25%6%46%7%7%8%41%
1980
11th to 20thNight
16%5%25%425%8%5%8%40%
1980
21st to endNight
13%5%2443345%8%48%
1980
October1st to 10thNight
14%42432335%6%54%
1980
11th to 20thNight
14%424423446%54%
2149
21st to endNight
12%323324345%59%
2376
November1st to 10thNight
13%5%24423335%57%
2299
11th to 20thNight
15%423423346%53%
2470
21st to endNight
16%4245%3445%6%48%
2470
December1st to 10thNight
18%6%26%5%34345%43%
2470
11th to 20thNight
17%5%24323335%53%
3042
21st to endNight
21%6%36%5%35%45%7%37%
4532

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 10thDay
40%5%7%19%23%6%
1707
11th to 20thDay
42%5%8%18%22%5%
1656
21st to endDay
40%35%21%23%8%
1782
February1st to 10thDay
43%5%9%18%19%6%
1778
11th to 20thDay
42%5%5%19%22%6%
1758
21st to endDay
46%5%8%14%18%9%
1480
March1st to 10thDay
35%5%8%19%21%12%
1916
11th to 20thDay
44%6%9%17%16%7%
1980
21st to endDay
42%6%10%21%18%4
2178
April1st to 10thDay
35%5%10%20%24%6%
1980
11th to 20thDay
37%6%8%18%22%10%
2114
21st to endDay
30%6%12%27%21%4
2340
May1st to 10thDay
32%8%14%22%21%5%
2340
11th to 20thDay
38%10%16%20%15%2
2305
21st to endDay
37%10%13%23%16%2
2531
June1st to 10thDay
40%10%18%20%10%2
2340
11th to 20thDay
33%11%19%23%12%1
2340
21st to endDay
35%12%18%19%12%4
2340
July1st to 10thDay
41%14%17%17%8%2
2275
11th to 20thDay
38%14%21%17%7%3
2271
21st to endDay
37%13%21%19%9%
2405
August1st to 10thDay
44%13%17%19%7%
2314
11th to 20thDay
45%12%17%16%8%2
2290
21st to endDay
46%12%15%16%9%2
2319
September1st to 10thDay
40%9%14%16%18%4
1980
11th to 20thDay
40%8%10%18%22%2
1980
21st to endDay
38%5%10%21%19%7%
1980
October1st to 10thDay
31%5%10%21%26%7%
1980
11th to 20thDay
31%49%23%24%9%
1810
21st to endDay
31%45%19%29%11%
1980
November1st to 10thDay
32%47%17%28%12%
1777
11th to 20thDay
33%48%20%25%10%
1710
21st to endDay
35%48%20%25%7%
1710
December1st to 10thDay
46%5%7%18%16%7%
1710
11th to 20thDay
39%46%18%22%11%
2150
21st to endDay
43%5%8%20%22%3
3124
January1st to 10thNight
42%47%16%25%6%
2459
11th to 20thNight
41%5%8%19%21%6%
2393
21st to endNight
39%35%19%25%9%
2574
February1st to 10thNight
39%5%8%19%21%7%
2180
11th to 20thNight
44%36%17%23%7%
2099
21st to endNight
43%5%8%17%18%10%
1776
March1st to 10thNight
36%49%16%23%12%
2044
11th to 20thNight
39%6%12%14%21%8%
1980
21st to endNight
39%6%10%20%20%5%
2178
April1st to 10thNight
33%5%11%19%24%8%
1980
11th to 20thNight
32%47%22%23%11%
1807
21st to endNight
31%6%10%25%21%6%
1620
May1st to 10thNight
32%7%14%22%22%4
1620
11th to 20thNight
39%9%16%19%16%1
1593
21st to endNight
38%9%12%25%14%3
1745
June1st to 10thNight
37%10%19%20%12%2
1620
11th to 20thNight
32%10%19%25%12%1
1620
21st to endNight
32%14%19%18%12%4
1620
July1st to 10thNight
42%14%20%14%8%2
1575
11th to 20thNight
37%17%21%16%7%2
1566
21st to endNight
37%14%23%19%7%1
1672
August1st to 10thNight
41%15%20%19%5%
1600
11th to 20thNight
41%13%16%18%11%1
1606
21st to endNight
44%13%17%15%9%3
2017
September1st to 10thNight
37%11%16%16%16%4
1980
11th to 20thNight
39%10%12%19%18%3
1980
21st to endNight
35%6%12%20%20%7%
1980
October1st to 10thNight
32%5%11%18%27%7%
1980
11th to 20thNight
33%6%8%21%24%9%
2149
21st to endNight
28%46%20%29%13%
2376
November1st to 10thNight
31%48%18%27%13%
2299
11th to 20thNight
33%46%18%26%13%
2470
21st to endNight
37%47%19%26%8%
2470
December1st to 10thNight
44%5%6%20%18%7%
2470
11th to 20thNight
36%47%16%28%8%
3044
21st to endNight
46%48%20%18%3
4532

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 10thDay
26%19%36%17%2
270
11th to 20thDay
27%19%28%22%3
252
21st to endDay
28%22%34%12%31
264
February1st to 10thDay
23%20%38%15%3
240
11th to 20thDay
38%15%33%13%
240
21st to endDay
34%20%35%10%1
198
March1st to 10thDay
21%15%33%24%7%
356
11th to 20thDay
22%17%36%16%7%1
420
21st to endDay
21%19%33%18%9%
462
April1st to 10thDay
21%15%28%23%12%1
420
11th to 20thDay
16%13%34%23%14%1
412
21st to endDay
16%10%28%24%16%6%
420
May1st to 10thDay
11%13%32%22%14%6%
423
11th to 20thDay
15%6%19%29%21%10%
447
21st to endDay
16%7%15%26%22%13%
485
June1st to 10thDay
11%316%32%27%11%
450
11th to 20thDay
7%5%16%28%24%20%
450
21st to endDay
9%320%29%24%15%
450
July1st to 10thDay
11%311%22%28%25%
445
11th to 20thDay
9%310%22%37%18%
444
21st to endDay
7%16%32%34%20%
488
August1st to 10thDay
15%413%22%27%18%
446
11th to 20thDay
13%38%28%33%15%
439
21st to endDay
14%5%9%24%31%16%
495
September1st to 10thDay
10%311%27%33%16%
450
11th to 20thDay
17%311%23%32%13%
450
21st to endDay
20%316%23%29%9%
450
October1st to 10thDay
17%6%18%31%18%10%
450
11th to 20thDay
13%10%24%26%23%5%
450
21st to endDay
17%9%24%27%19%3
495
November1st to 10thDay
22%8%26%26%15%3
375
11th to 20thDay
17%14%35%28%5%1
270
21st to endDay
16%11%36%24%11%1
270
December1st to 10thDay
31%15%32%17%5%
270
11th to 20thDay
24%14%36%19%42
270
21st to endDay
33%17%26%16%6%2
297
January1st to 10thNight
23%18%29%24%6%
760
11th to 20thNight
23%15%29%26%7%
737
21st to endNight
21%17%34%25%2
792
February1st to 10thNight
20%15%30%31%5%
720
11th to 20thNight
25%15%33%25%2
703
21st to endNight
21%18%34%25%3
592
March1st to 10thNight
18%14%33%31%4
720
11th to 20thNight
19%12%33%25%11%
720
21st to endNight
18%14%30%28%10%
792
April1st to 10thNight
15%15%30%30%10%
720
11th to 20thNight
14%12%28%30%15%
605
21st to endNight
12%9%27%31%21%1
540
May1st to 10thNight
10%9%27%34%20%1
540
11th to 20thNight
13%422%33%23%4
531
21st to endNight
14%312%34%31%6%
584
June1st to 10thNight
10%213%36%32%6%
540
11th to 20thNight
8%314%30%34%12%
540
21st to endNight
9%213%35%34%8%
540
July1st to 10thNight
11%27%29%38%12%
525
11th to 20thNight
10%16%27%44%12%
522
21st to endNight
6%110%32%43%8%
591
August1st to 10thNight
12%210%27%39%11%
537
11th to 20thNight
14%18%30%37%9%
534
21st to endNight
13%211%26%37%10%
631
September1st to 10thNight
9%312%26%40%10%
720
11th to 20thNight
18%214%26%34%6%
720
21st to endNight
15%316%32%32%3
720
October1st to 10thNight
14%6%18%28%27%6%
720
11th to 20thNight
15%6%23%32%21%3
720
21st to endNight
14%8%21%34%21%2
792
November1st to 10thNight
14%8%22%33%21%2
740
11th to 20thNight
17%10%29%30%13%1
760
21st to endNight
17%10%26%33%13%1
760
December1st to 10thNight
22%14%25%30%8%
760
11th to 20thNight
20%13%28%28%11%1
760
21st to endNight
28%12%26%28%6%
836
Page generated at 2024-01-11 22:33:47. Version ac07

Copyright 2024 Attilla Danko


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