Auburn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Auburn clear sky chart from 2005-11-05 to 2017-09-10.

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%
15839
16%
46716
11%
15796
43%
15796
21%
32214

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
16%
900
11%
2506
4%
895
23%
895
13%
1958
January16th to endNight
20%
900
10%
2628
4%
900
26%
900
12%
2067
February1st to 15thNight
19%
702
10%
2184
3%
701
25%
701
13%
1634
February16th to endNight
22%
631
14%
1893
6%
631
30%
631
14%
1411
March1st to 15thNight
28%
720
13%
2118
9%
720
31%
720
18%
1527
March16th to endNight
32%
759
18%
2103
9%
759
39%
759
21%
1480
April1st to 15thNight
31%
539
15%
1797
10%
539
38%
539
19%
1238
April16th to endNight
36%
540
21%
1641
10%
540
46%
540
24%
1090
May1st to 15thNight
34%
540
13%
1620
7%
540
40%
540
19%
1176
May16th to endNight
47%
562
16%
1643
11%
561
52%
561
30%
1037
June1st to 15thNight
54%
540
16%
1440
12%
540
58%
540
35%
895
June16th to endNight
55%
540
17%
1440
11%
540
60%
540
34%
921
July1st to 15thNight
64%
510
17%
1360
14%
510
66%
510
38%
827
July16th to endNight
69%
564
21%
1469
17%
531
72%
531
41%
840
August1st to 15thNight
68%
539
21%
1609
17%
536
70%
536
38%
915
August16th to endNight
69%
573
20%
1827
19%
573
72%
573
33%
1069
September1st to 15thNight
61%
611
26%
1836
23%
611
66%
611
35%
1068
September16th to endNight
60%
657
25%
1815
20%
657
63%
657
35%
1102
October1st to 15thNight
49%
660
25%
1848
19%
660
55%
660
33%
1139
October16th to endNight
29%
704
17%
2247
11%
704
37%
704
18%
1533
November1st to 15thNight
36%
700
23%
2276
17%
700
45%
700
24%
1425
November16th to endNight
27%
720
14%
2340
10%
720
32%
720
14%
1739
December1st to 15thNight
20%
768
8%
2388
4%
768
25%
768
11%
1884
December16th to endNight
16%
960
8%
2688
3%
960
21%
960
10%
2239

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%8%36%6%35%45%7%33%
47904
Night
15%8%36%5%34446%36%
46890
Cloud CoverDay
14%8%36%6%35%5%5%7%33%
47913
Night
15%8%36%5%34446%36%
46895
TransparencyDay
48%6%12%19%11%1
47596
Night
47%5%11%20%12%1
46716
SeeingDay
16%7%25%25%17%7%
5846
Night
18%8%28%29%14%1
15842

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
19%16%5%9%5%33435%21%
1432
16th to endDay
14%17%9%11%7%35%43417%
1593
February1st to 15thDay
14%13%6%10%7%45%347%21%
1676
16th to endDay
14%13%6%9%8%45%45%7%21%
1580
March1st to 15thDay
18%11%47%6%36%446%25%
1832
16th to endDay
19%8%37%6%35%45%7%28%
2130
April1st to 15thDay
19%9%36%5%25%45%6%31%
2151
16th to endDay
16%7%26%5%2445%7%36%
2317
May1st to 15thDay
19%8%37%6%3445%7%29%
2331
16th to endDay
11%5%25%6%35%5%6%8%39%
2469
June1st to 15thDay
10%5%25%5%35%5%5%8%41%
2520
16th to endDay
10%5%25%6%36%6%6%9%37%
2520
July1st to 15thDay
7%425%6%345%6%9%42%
2520
16th to endDay
6%435%5%35%6%7%9%41%
2598
August1st to 15thDay
6%425%5%35%6%6%10%42%
2340
16th to endDay
10%6%245%45%5%7%8%40%
2372
September1st to 15thDay
12%5%25%5%3445%6%43%
1998
16th to endDay
12%5%135%35%45%7%43%
1815
October1st to 15thDay
14%5%25%6%25%45%5%41%
1780
16th to endDay
21%7%25%5%445%6%5%31%
1623
November1st to 15thDay
14%7%34423447%43%
1582
16th to endDay
20%13%48%5%34346%24%
1620
December1st to 15thDay
17%15%7%9%7%3444420%
1569
16th to endDay
22%15%7%8%6%24446%16%
1536
January1st to 15thNight
21%11%48%7%34336%25%
2506
16th to endNight
15%13%6%9%7%45%5%45%22%
2628
February1st to 15thNight
16%12%6%8%6%24346%28%
2182
16th to endNight
16%10%5%8%6%45%445%28%
1893
March1st to 15thNight
17%8%47%5%44346%32%
2105
16th to endNight
14%8%37%5%3446%6%35%
2103
April1st to 15thNight
18%6%35%435%5%6%7%34%
1797
16th to endNight
16%6%26%5%235%46%40%
1641
May1st to 15thNight
20%7%35%5%45%5%5%6%31%
1620
16th to endNight
13%5%244235%5%7%44%
1641
June1st to 15thNight
9%4245%235%5%8%48%
1440
16th to endNight
6%3246%35%5%6%9%44%
1440
July1st to 15thNight
6%325%3245%5%9%50%
1440
16th to endNight
6%31441346%9%52%
1569
August1st to 15thNight
44244345%5%10%50%
1620
16th to endNight
9%4144245%5%8%49%
1827
September1st to 15thNight
11%313334336%53%
1836
16th to endNight
13%5%14324445%50%
1815
October1st to 15thNight
12%5%2442335%7%48%
1848
16th to endNight
21%7%25%5%34345%36%
2247
November1st to 15thNight
15%7%345%2335%6%42%
2276
16th to endNight
21%11%47%5%3445%6%26%
2340
December1st to 15thNight
20%14%6%8%5%35%345%22%
2388
16th to endNight
23%14%5%9%6%25%445%18%
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
19%16%5%9%5%33445%20%
1432
16th to endDay
14%17%8%11%7%45%435%17%
1593
February1st to 15thDay
14%13%6%10%7%45%347%20%
1676
16th to endDay
14%13%6%10%7%45%447%20%
1580
March1st to 15thDay
19%11%47%6%26%446%25%
1842
16th to endDay
19%8%37%7%35%447%27%
2129
April1st to 15thDay
19%9%36%5%25%45%6%31%
2151
16th to endDay
16%7%36%5%3345%7%36%
2317
May1st to 15thDay
19%8%37%6%445%5%6%29%
2331
16th to endDay
11%5%25%6%35%5%6%8%39%
2469
June1st to 15thDay
10%435%5%35%5%6%8%41%
2520
16th to endDay
10%425%6%45%6%6%8%37%
2520
July1st to 15thDay
7%425%5%345%6%9%42%
2520
16th to endDay
6%435%5%45%7%7%9%41%
2598
August1st to 15thDay
6%425%5%35%6%6%10%42%
2340
16th to endDay
10%6%25%5%445%6%8%40%
2372
September1st to 15thDay
12%5%25%5%3445%7%43%
1998
16th to endDay
13%5%135%35%45%7%42%
1815
October1st to 15thDay
14%5%26%5%25%45%5%41%
1780
16th to endDay
21%7%25%5%445%6%6%30%
1623
November1st to 15thDay
14%7%34424347%43%
1582
16th to endDay
20%13%47%6%24346%24%
1620
December1st to 15thDay
17%15%7%9%7%3444420%
1569
16th to endDay
22%15%7%9%5%33446%16%
1536
January1st to 15thNight
21%11%48%7%34336%24%
2506
16th to endNight
15%13%6%9%7%45%446%22%
2628
February1st to 15thNight
15%12%6%8%6%24446%28%
2175
16th to endNight
16%10%6%8%6%45%435%28%
1893
March1st to 15thNight
17%9%47%5%44345%32%
2118
16th to endNight
14%8%37%5%2446%6%35%
2103
April1st to 15thNight
18%6%35%335%5%6%7%33%
1797
16th to endNight
15%6%26%5%235%46%40%
1641
May1st to 15thNight
19%7%35%5%45%5%5%6%31%
1619
16th to endNight
13%5%2442445%7%44%
1641
June1st to 15thNight
9%5%235%235%5%7%48%
1440
16th to endNight
6%3246%35%5%6%9%44%
1440
July1st to 15thNight
6%315%4245%6%10%50%
1440
16th to endNight
5%31441346%9%52%
1569
August1st to 15thNight
4414435%45%10%50%
1620
16th to endNight
9%3145%2446%7%49%
1827
September1st to 15thNight
11%313434336%53%
1836
16th to endNight
12%5%143235%45%50%
1815
October1st to 15thNight
12%5%2442345%7%48%
1848
16th to endNight
20%8%26%434345%36%
2247
November1st to 15thNight
15%6%25%42335%6%42%
2276
16th to endNight
20%11%5%7%5%34446%26%
2340
December1st to 15thNight
20%14%6%8%5%35%345%22%
2388
16th to endNight
23%14%5%9%6%34445%18%
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
65%5%12%11%5%
1433
16th to endDay
68%5%10%10%5%
1593
February1st to 15thDay
64%49%13%7%
1678
16th to endDay
63%5%11%15%3
1580
March1st to 15thDay
59%5%11%15%6%
1842
16th to endDay
55%5%12%19%5%1
2130
April1st to 15thDay
53%5%10%19%11%
2151
16th to endDay
45%6%12%18%12%4
2317
May1st to 15thDay
53%6%11%19%8%
2331
16th to endDay
41%8%11%22%13%2
2473
June1st to 15thDay
39%6%10%24%16%1
2520
16th to endDay
40%7%13%20%16%1
2520
July1st to 15thDay
36%7%12%21%19%2
2371
16th to endDay
34%8%16%23%14%2
2435
August1st to 15thDay
34%9%13%24%16%2
2327
16th to endDay
38%7%12%21%15%3
2372
September1st to 15thDay
38%5%12%22%18%2
1998
16th to endDay
38%5%9%25%19%1
1815
October1st to 15thDay
43%412%22%15%1
1780
16th to endDay
51%5%14%18%8%
1623
November1st to 15thDay
40%410%24%17%1
1582
16th to endDay
60%5%10%17%5%
1620
December1st to 15thDay
66%410%13%4
1569
16th to endDay
69%5%11%9%3
1536
January1st to 15thNight
61%411%14%8%
2506
16th to endNight
62%5%13%14%3
2628
February1st to 15thNight
57%5%12%15%6%1
2184
16th to endNight
57%410%19%7%
1893
March1st to 15thNight
53%412%18%9%1
2118
16th to endNight
47%6%10%23%9%2
2103
April1st to 15thNight
47%7%10%19%14%
1797
16th to endNight
43%6%9%19%17%3
1641
May1st to 15thNight
51%6%11%18%9%2
1620
16th to endNight
38%5%14%23%14%3
1643
June1st to 15thNight
33%6%12%26%19%1
1440
16th to endNight
34%7%17%22%15%2
1440
July1st to 15thNight
29%7%13%24%21%3
1360
16th to endNight
25%8%16%26%19%4
1469
August1st to 15thNight
28%6%14%26%21%2
1609
16th to endNight
31%7%12%23%20%4
1827
September1st to 15thNight
31%5%11%25%22%4
1836
16th to endNight
33%5%9%27%21%2
1815
October1st to 15thNight
35%5%10%27%20%
1848
16th to endNight
49%411%23%9%1
2247
November1st to 15thNight
41%49%25%16%2
2276
16th to endNight
57%411%17%7%
2340
December1st to 15thNight
64%410%14%6%
2388
16th to endNight
68%5%9%11%4
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
26%13%38%12%7%1
90
16th to endDay
32%11%37%13%5%
96
February1st to 15thDay
18%24%38%14%3
90
16th to endDay
17%13%40%20%7%
81
March1st to 15thDay
34%15%21%22%6%
132
16th to endDay
25%8%33%23%6%1
288
April1st to 15thDay
25%10%31%21%9%1
270
16th to endDay
20%9%31%17%14%7%
270
May1st to 15thDay
24%7%25%25%11%5%
288
16th to endDay
18%7%26%24%13%10%
369
June1st to 15thDay
13%5%28%30%15%6%
495
16th to endDay
12%6%30%27%16%5%
495
July1st to 15thDay
11%324%31%18%10%
475
16th to endDay
7%119%31%26%13%
458
August1st to 15thDay
8%14%29%27%20%
313
16th to endDay
13%215%21%28%18%
332
September1st to 15thDay
13%414%24%30%12%
294
16th to endDay
16%411%24%32%10%
254
October1st to 15thDay
15%5%22%30%18%7%
255
16th to endDay
23%12%28%27%7%
135
November1st to 15thDay
8%10%25%31%20%4
90
16th to endDay
26%11%40%15%6%
90
December1st to 15thDay
22%20%35%16%5%
90
16th to endDay
27%25%36%10%1
96
January1st to 15thNight
26%13%35%19%4
900
16th to endNight
20%13%36%24%4
900
February1st to 15thNight
23%12%38%23%3
704
16th to endNight
21%13%33%26%4
631
March1st to 15thNight
22%10%31%27%6%
720
16th to endNight
17%10%34%28%9%
759
April1st to 15thNight
20%10%33%26%7%
539
16th to endNight
19%5%35%27%11%1
540
May1st to 15thNight
21%5%30%30%11%
540
16th to endNight
15%325%34%17%2
563
June1st to 15thNight
11%225%44%15%
540
16th to endNight
7%225%38%23%1
540
July1st to 15thNight
9%17%44%25%2
510
16th to endNight
6%115%40%33%3
564
August1st to 15thNight
4114%47%26%5%
539
16th to endNight
10%112%32%39%3
573
September1st to 15thNight
13%317%30%31%3
611
16th to endNight
14%414%33%28%3
657
October1st to 15thNight
15%6%23%32%20%3
660
16th to endNight
24%11%31%22%9%
704
November1st to 15thNight
17%11%31%25%12%1
700
16th to endNight
27%12%26%25%7%
720
December1st to 15thNight
29%12%30%22%5%
768
16th to endNight
30%11%32%21%3
960
Page generated at 2017-09-11 19:35:17. Version ac04

Copyright 2017 A. Danko


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