Lanphier Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lanphier Observatory clear sky chart from 2005-11-06 to 2024-03-01.

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
38%
24697
19%
80506
12%
24585
46%
24585
23%
53098

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
21%
943
13%
4384
6%
926
31%
926
12%
3025
January11th to 20thNight
20%
950
12%
4327
5%
930
28%
930
9%
3305
January21st to endNight
20%
1041
10%
4500
4%
1023
27%
1023
9%
3539
February1st to 10thNight
22%
950
14%
2470
4%
950
29%
950
19%
1824
February11th to 20thNight
24%
756
19%
2234
7%
755
33%
755
22%
1498
February21st to endNight
19%
628
18%
1884
6%
628
29%
628
19%
1278
March1st to 10thNight
23%
723
18%
2167
7%
723
32%
723
20%
1473
March11th to 20thNight
31%
576
18%
2016
11%
576
41%
576
20%
1304
March21st to endNight
24%
594
13%
2036
6%
594
33%
594
14%
1479
April1st to 10thNight
29%
540
19%
1800
11%
540
41%
540
23%
1119
April11th to 20thNight
33%
533
22%
1775
16%
533
44%
533
25%
1086
April21st to endNight
27%
540
18%
1800
11%
540
38%
540
20%
1197
May1st to 10thNight
33%
540
16%
1674
9%
540
41%
540
24%
1099
May11th to 20thNight
45%
531
20%
1431
12%
531
50%
531
28%
967
May21st to endNight
50%
584
18%
1551
11%
582
55%
582
29%
1048
June1st to 10thNight
62%
540
19%
1440
14%
540
66%
540
41%
850
June11th to 20thNight
59%
540
23%
1440
15%
540
63%
540
38%
863
June21st to endNight
54%
540
21%
1440
12%
540
59%
540
38%
879
July1st to 10thNight
69%
525
18%
1400
15%
525
70%
525
37%
867
July11th to 20thNight
68%
522
26%
1392
19%
522
72%
522
48%
777
July21st to endNight
70%
591
26%
1508
20%
558
73%
558
42%
883
August1st to 10thNight
71%
537
23%
1605
23%
534
73%
534
39%
890
August11th to 20thNight
70%
534
24%
1776
27%
534
73%
534
34%
982
August21st to endNight
74%
594
23%
1980
27%
594
77%
594
40%
1033
September1st to 10thNight
62%
540
26%
1800
27%
540
66%
540
33%
992
September11th to 20thNight
65%
566
35%
1826
34%
566
69%
566
37%
987
September21st to endNight
55%
720
29%
1980
20%
720
62%
720
38%
1172
October1st to 10thNight
50%
720
25%
2128
18%
720
56%
720
36%
1243
October11th to 20thNight
37%
720
28%
2160
15%
720
50%
720
30%
1292
October21st to endNight
27%
792
21%
2453
12%
792
38%
792
21%
1595
November1st to 10thNight
33%
740
27%
2406
16%
740
46%
740
31%
1339
November11th to 20thNight
28%
760
26%
2470
12%
760
45%
760
26%
1470
November21st to endNight
27%
845
21%
2555
11%
845
39%
845
22%
1686
December1st to 10thNight
22%
950
15%
2660
7%
950
30%
950
20%
1881
December11th to 20thNight
27%
950
18%
3168
7%
948
35%
948
18%
2141
December21st to endNight
17%
1042
8%
4870
4%
1026
27%
1026
7%
4035

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
13%8%46%6%35%5%5%7%39%
78496
Night
14%9%46%5%3445%7%40%
80959
TransparencyDay
44%6%12%23%14%2
78199
Night
44%5%11%22%15%3
80777
SeeingDay
16%10%27%26%16%5%
14678
Night
17%9%30%30%13%1
24713

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
12%12%7%13%8%35%45%6%26%
2527
11th to 20thDay
14%9%5%9%10%6%9%7%6%5%21%
2571
21st to endDay
19%18%9%9%433335%23%
3135
February1st to 10thDay
15%12%6%9%6%34446%30%
1710
11th to 20thDay
13%9%47%7%35%5%5%7%34%
1831
21st to endDay
16%11%5%9%6%34446%33%
1570
March1st to 10thDay
15%10%5%7%7%34446%35%
1800
11th to 20thDay
14%11%47%6%3445%7%35%
1957
21st to endDay
20%11%5%7%7%35%5%5%6%26%
2318
April1st to 10thDay
13%7%46%6%35%5%5%8%38%
2160
11th to 20thDay
16%9%36%5%35%45%6%39%
2134
21st to endDay
19%6%35%7%45%45%7%35%
2160
May1st to 10thDay
16%8%36%5%45%6%6%8%33%
2286
11th to 20thDay
16%7%36%6%35%5%5%7%37%
2461
21st to endDay
12%7%36%6%46%7%6%8%36%
2725
June1st to 10thDay
8%4345%35%6%6%9%47%
2520
11th to 20thDay
9%425%5%35%5%6%7%49%
2520
21st to endDay
7%5%36%6%45%6%7%8%43%
2520
July1st to 10thDay
9%3245%35%7%7%10%46%
2520
11th to 20thDay
5%425%5%36%6%7%11%46%
2520
21st to endDay
8%325%435%5%7%10%47%
2718
August1st to 10thDay
7%5%25%5%36%5%7%11%42%
2324
11th to 20thDay
7%5%25%445%6%6%9%46%
2125
21st to endDay
7%425%5%346%6%9%49%
2376
September1st to 10thDay
12%5%25%43445%7%48%
2160
11th to 20thDay
8%5%35%435%45%6%52%
2116
21st to endDay
7%5%25%4345%6%7%52%
1980
October1st to 10thDay
12%5%245%3445%7%51%
1828
11th to 20thDay
16%7%25%5%23446%45%
1800
21st to endDay
19%9%36%433346%40%
1901
November1st to 10thDay
10%6%25%433448%51%
1672
11th to 20thDay
15%9%46%42345%6%42%
1710
21st to endDay
16%10%47%5%34435%38%
1620
December1st to 10thDay
14%10%6%7%5%35%5%5%7%34%
1520
11th to 20thDay
14%10%5%7%6%345%5%8%33%
1918
21st to endDay
21%16%6%13%5%34435%19%
2783
January1st to 10thNight
13%13%6%9%6%44445%32%
4428
11th to 20thNight
13%16%7%8%6%48%5%4424%
4394
21st to endNight
23%15%7%11%5%23336%22%
4532
February1st to 10thNight
16%11%5%8%5%3445%6%32%
2470
11th to 20thNight
13%8%48%6%34446%40%
2233
21st to endNight
15%10%37%6%34445%38%
1884
March1st to 10thNight
16%10%46%5%24445%40%
2167
11th to 20thNight
16%8%37%5%25%45%7%39%
2016
21st to endNight
21%11%46%5%345%46%30%
2036
April1st to 10thNight
11%7%45%5%45%5%5%7%43%
1800
11th to 20thNight
14%6%35%435%45%7%44%
1775
21st to endNight
20%7%45%5%345%35%39%
1800
May1st to 10thNight
15%6%36%5%35%5%6%8%39%
1674
11th to 20thNight
17%6%25%44445%7%43%
1430
21st to endNight
10%6%36%6%35%6%6%10%39%
1551
June1st to 10thNight
8%5%24325%5%5%9%52%
1440
11th to 20thNight
8%4245%345%6%8%51%
1440
21st to endNight
7%335%435%5%7%9%49%
1440
July1st to 10thNight
8%425%4345%6%9%49%
1440
11th to 20thNight
5%4234345%6%9%56%
1440
21st to endNight
5%325%436%5%7%10%52%
1597
August1st to 10thNight
7%3235%245%6%11%52%
1615
11th to 20thNight
7%424435%5%5%8%53%
1776
21st to endNight
5%214435%5%7%9%55%
1980
September1st to 10thNight
11%43442335%8%54%
1800
11th to 20thNight
8%5%25%43345%8%55%
1826
21st to endNight
8%5%245%3445%7%54%
1980
October1st to 10thNight
10%425%5%24347%54%
2128
11th to 20thNight
14%6%2442345%7%49%
2160
21st to endNight
19%8%25%42435%5%43%
2453
November1st to 10thNight
10%6%25%423346%55%
2406
11th to 20thNight
12%7%36%5%23346%49%
2470
21st to endNight
17%9%35%424446%41%
2555
December1st to 10thNight
16%11%46%6%35%45%7%33%
2660
11th to 20thNight
16%8%48%5%34445%40%
3279
21st to endNight
21%18%6%10%7%4433419%
4884

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
59%5%8%19%8%
2528
11th to 20thDay
64%413%14%5%
2571
21st to endDay
65%410%14%7%
3135
February1st to 10thDay
56%5%11%18%9%1
1710
11th to 20thDay
50%5%11%21%12%1
1841
21st to endDay
54%310%21%10%2
1570
March1st to 10thDay
50%5%11%23%10%1
1800
11th to 20thDay
50%5%13%21%9%1
1957
21st to endDay
59%6%10%18%7%1
2318
April1st to 10thDay
44%6%12%24%13%1
2160
11th to 20thDay
46%5%9%24%14%2
2134
21st to endDay
48%6%12%20%12%2
2160
May1st to 10thDay
47%8%14%21%9%1
2286
11th to 20thDay
46%7%12%22%12%1
2465
21st to endDay
42%9%12%19%15%2
2725
June1st to 10thDay
31%9%13%27%17%3
2520
11th to 20thDay
34%7%11%23%23%3
2520
21st to endDay
35%10%13%22%17%3
2520
July1st to 10thDay
31%9%14%28%14%3
2451
11th to 20thDay
30%8%16%28%16%2
2445
21st to endDay
30%8%14%30%16%1
2567
August1st to 10thDay
34%9%16%29%11%2
2310
11th to 20thDay
34%8%12%29%16%1
2125
21st to endDay
29%8%13%24%20%5%
2376
September1st to 10thDay
35%6%11%24%17%6%
2160
11th to 20thDay
33%5%8%26%23%5%
2116
21st to endDay
30%6%10%29%23%3
1980
October1st to 10thDay
33%5%11%24%23%3
1828
11th to 20thDay
42%49%23%21%2
1800
21st to endDay
47%49%24%14%3
1901
November1st to 10thDay
35%414%25%18%4
1672
11th to 20thDay
42%411%25%16%3
1710
21st to endDay
49%5%10%24%11%
1620
December1st to 10thDay
50%6%13%20%10%
1520
11th to 20thDay
48%6%10%26%8%2
1915
21st to endDay
68%410%12%6%1
2783
January1st to 10thNight
54%5%12%21%9%
4428
11th to 20thNight
64%39%16%7%
4394
21st to endNight
65%48%16%6%1
4532
February1st to 10thNight
53%411%18%11%2
2470
11th to 20thNight
47%311%23%15%2
2234
21st to endNight
48%411%21%12%3
1884
March1st to 10thNight
48%5%7%24%15%1
2167
11th to 20thNight
45%6%12%21%14%3
2016
21st to endNight
55%6%10%19%8%1
2036
April1st to 10thNight
40%6%12%24%15%3
1800
11th to 20thNight
40%5%10%25%17%4
1775
21st to endNight
48%5%10%19%16%3
1800
May1st to 10thNight
42%6%13%23%13%1
1674
11th to 20thNight
42%6%12%22%17%1
1431
21st to endNight
38%9%15%18%16%4
1552
June1st to 10thNight
27%8%14%28%19%4
1440
11th to 20thNight
30%7%11%23%24%5%
1440
21st to endNight
31%7%16%23%19%4
1440
July1st to 10thNight
31%7%13%29%15%4
1400
11th to 20thNight
22%7%14%34%20%3
1392
21st to endNight
26%7%16%28%20%3
1508
August1st to 10thNight
26%8%16%33%16%2
1605
11th to 20thNight
29%7%11%30%22%2
1776
21st to endNight
23%8%16%26%20%7%
1980
September1st to 10thNight
31%6%10%25%21%8%
1800
11th to 20thNight
29%5%8%27%27%5%
1826
21st to endNight
30%6%9%25%26%5%
1980
October1st to 10thNight
31%5%10%23%26%5%
2128
11th to 20thNight
35%5%8%27%22%4
2160
21st to endNight
45%48%21%19%2
2453
November1st to 10thNight
32%5%11%27%20%5%
2406
11th to 20thNight
37%410%27%20%2
2470
21st to endNight
46%310%24%16%1
2555
December1st to 10thNight
51%412%22%10%1
2660
11th to 20thNight
48%411%24%11%1
3281
21st to endNight
69%5%7%12%6%1
4884

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
24%19%33%17%7%
270
11th to 20thDay
28%17%37%16%2
270
21st to endDay
20%17%37%22%5%
297
February1st to 10thDay
27%16%38%15%4
270
11th to 20thDay
24%17%33%21%4
270
21st to endDay
24%14%46%14%1
225
March1st to 10thDay
23%19%38%17%3
240
11th to 20thDay
29%14%35%16%5%
240
21st to endDay
31%16%29%18%5%
404
April1st to 10thDay
19%15%33%26%6%1
420
11th to 20thDay
19%17%31%20%11%1
412
21st to endDay
22%14%34%20%8%1
420
May1st to 10thDay
18%13%34%24%9%2
423
11th to 20thDay
18%12%27%27%14%3
607
21st to endDay
13%6%33%25%15%8%
679
June1st to 10thDay
9%6%22%32%25%7%
630
11th to 20thDay
11%5%21%36%22%6%
630
21st to endDay
8%6%29%34%19%4
630
July1st to 10thDay
11%215%29%29%15%
621
11th to 20thDay
6%321%34%25%10%
618
21st to endDay
9%218%32%31%8%
684
August1st to 10thDay
8%315%38%27%10%
622
11th to 20thDay
8%5%17%28%28%15%
439
21st to endDay
7%217%31%33%11%
495
September1st to 10thDay
14%418%28%27%8%
450
11th to 20thDay
9%314%32%30%12%
450
21st to endDay
8%11%22%27%23%9%
450
October1st to 10thDay
13%9%27%33%15%4
298
11th to 20thDay
18%19%33%22%6%1
270
21st to endDay
33%12%33%17%5%
297
November1st to 10thDay
11%15%36%21%11%5%
270
11th to 20thDay
24%16%31%18%9%2
270
21st to endDay
23%13%38%20%6%
270
December1st to 10thDay
15%23%35%17%6%4
270
11th to 20thDay
20%18%38%20%4
270
21st to endDay
26%20%37%14%2
297
January1st to 10thNight
18%14%40%23%5%
950
11th to 20thNight
21%16%37%21%5%
950
21st to endNight
22%14%35%27%3
1045
February1st to 10thNight
23%14%36%24%3
950
11th to 20thNight
20%14%36%27%2
758
21st to endNight
22%17%36%22%3
628
March1st to 10thNight
22%14%37%23%4
723
11th to 20thNight
21%10%33%29%6%
576
21st to endNight
28%10%33%23%6%
594
April1st to 10thNight
17%15%37%27%5%
540
11th to 20thNight
16%12%35%27%10%
533
21st to endNight
22%9%36%25%6%1
540
May1st to 10thNight
18%5%39%28%9%1
540
11th to 20thNight
19%5%27%36%12%2
531
21st to endNight
11%5%27%33%22%3
584
June1st to 10thNight
9%419%47%21%
540
11th to 20thNight
11%322%43%20%2
540
21st to endNight
8%227%41%19%1
540
July1st to 10thNight
10%210%35%37%5%
525
11th to 20thNight
5%219%40%32%3
522
21st to endNight
7%115%46%31%2
591
August1st to 10thNight
8%212%44%30%4
537
11th to 20thNight
8%113%37%34%6%
534
21st to endNight
5%113%39%39%2
594
September1st to 10thNight
12%317%36%28%4
540
11th to 20thNight
9%117%38%30%4
566
21st to endNight
9%8%23%32%24%4
720
October1st to 10thNight
11%431%31%21%2
720
11th to 20thNight
17%11%32%28%12%
720
21st to endNight
23%12%34%23%7%
792
November1st to 10thNight
12%9%42%27%9%
740
11th to 20thNight
17%14%37%26%6%1
760
21st to endNight
22%14%34%25%5%
845
December1st to 10thNight
21%12%38%23%5%1
950
11th to 20thNight
23%10%35%26%6%
950
21st to endNight
25%17%32%22%3
1045
Page generated at 2024-02-27 05:30:15. Version ac07

Copyright © 2024 Attilla Danko.


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