Whispering Pines Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whispering Pines Observatory clear sky chart from 2005-11-05 to 2017-09-24.

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
53%
15945
27%
46943
18%
15903
61%
15903
40%
25888

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
52%
899
31%
2506
21%
895
61%
895
48%
1309
January16th to endNight
51%
813
33%
2541
24%
813
61%
813
42%
1321
February1st to 15thNight
45%
699
24%
2226
16%
698
55%
698
36%
1230
February16th to endNight
38%
632
34%
1894
15%
632
56%
632
41%
1001
March1st to 15thNight
45%
720
27%
2130
14%
720
57%
720
41%
1171
March16th to endNight
42%
669
27%
2013
14%
669
55%
669
39%
1108
April1st to 15thNight
35%
539
24%
1798
13%
539
51%
539
33%
989
April16th to endNight
39%
540
21%
1800
15%
540
50%
540
28%
1075
May1st to 15thNight
47%
540
19%
1628
14%
540
53%
540
27%
1039
May16th to endNight
46%
562
17%
1498
10%
561
53%
561
34%
927
June1st to 15thNight
59%
540
22%
1440
15%
540
64%
540
47%
780
June16th to endNight
67%
540
25%
1440
20%
540
71%
540
50%
769
July1st to 15thNight
64%
510
16%
1360
13%
510
67%
510
34%
845
July16th to endNight
70%
564
22%
1436
18%
531
72%
531
37%
867
August1st to 15thNight
67%
539
17%
1689
16%
536
70%
536
31%
995
August16th to endNight
70%
573
25%
1910
25%
573
74%
573
37%
1027
September1st to 15thNight
65%
540
26%
1800
26%
540
71%
540
37%
971
September16th to endNight
66%
519
34%
1878
32%
519
74%
519
45%
869
October1st to 15thNight
53%
632
29%
1952
19%
632
61%
632
41%
1051
October16th to endNight
62%
740
36%
2148
22%
740
71%
740
50%
1098
November1st to 15thNight
57%
875
34%
2275
19%
875
63%
875
52%
1217
November16th to endNight
55%
900
35%
2373
21%
900
62%
900
51%
1270
December1st to 15thNight
50%
900
26%
2520
14%
900
59%
900
44%
1384
December16th to endNight
43%
960
27%
2688
15%
960
54%
960
37%
1575

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
5%5%2442446%8%52%
47998
Night
45%2432345%7%56%
47117
Cloud CoverDay
5%5%2442446%8%52%
47996
Night
45%2432345%7%56%
47117
TransparencyDay
28%6%11%23%21%8%
47675
Night
26%5%12%25%22%7%
46943
SeeingDay
10%8%27%28%18%6%
5868
Night
6%330%41%16%1
15952

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
16%24313246%62%
1432
16th to endDay
26%24312347%61%
1692
February1st to 15thDay
17%46%433346%55%
1633
16th to endDay
17%3332245%7%57%
1580
March1st to 15thDay
36%3432446%7%53%
1828
16th to endDay
5%9%2332445%8%50%
2211
April1st to 15thDay
8%6%25%41345%7%50%
2150
16th to endDay
9%8%2433445%7%45%
2160
May1st to 15thDay
9%7%25%5%345%6%8%40%
2319
16th to endDay
8%4145%35%6%6%8%44%
2616
June1st to 15thDay
6%413325%5%7%8%49%
2520
16th to endDay
32134346%6%10%53%
2520
July1st to 15thDay
6%424436%6%8%10%44%
2520
16th to endDay
5%3145%47%6%7%10%43%
2632
August1st to 15thDay
6%3145%45%6%7%10%43%
2262
16th to endDay
5%3144345%7%9%50%
2292
September1st to 15thDay
6%22342446%7%53%
2160
16th to endDay
4213323346%64%
1940
October1st to 15thDay
6%313314347%60%
1676
16th to endDay
5%412212245%66%
1712
November1st to 15thDay
25%3324447%61%
1583
16th to endDay
2423213346%63%
1584
December1st to 15thDay
16%25%32345%7%55%
1440
16th to endDay
25%36%32445%6%54%
1536
January1st to 15thNight
1434322246%64%
2506
16th to endNight
15%25%42334461%
2541
February1st to 15thNight
27%35%324347%55%
2216
16th to endNight
17%34423346%58%
1894
March1st to 15thNight
45%2342346%6%56%
2130
16th to endNight
5%6%24413347%57%
2013
April1st to 15thNight
6%7%1342345%7%55%
1798
16th to endNight
13%7%23323346%48%
1800
May1st to 15thNight
13%6%2442445%8%44%
1627
16th to endNight
7%5%1441445%8%50%
1497
June1st to 15thNight
421221436%10%58%
1440
16th to endNight
221332336%10%59%
1440
July1st to 15thNight
5%3246%35%5%6%7%48%
1440
16th to endNight
5%323435%5%8%10%47%
1533
August1st to 15thNight
5%414426%6%6%10%47%
1698
16th to endNight
5%3233245%6%11%51%
1910
September1st to 15thNight
7%3133235%6%10%51%
1800
16th to endNight
4213323345%65%
1878
October1st to 15thNight
6%5%14323446%58%
1952
16th to endNight
4412213347%63%
2148
November1st to 15thNight
2323323346%64%
2275
16th to endNight
25%23312237%63%
2373
December1st to 15thNight
15%35%32335%7%58%
2520
16th to endNight
27%36%324446%54%
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
16%24213246%62%
1432
16th to endDay
25%33312348%61%
1692
February1st to 15thDay
17%35%433336%55%
1633
16th to endDay
17%2431445%6%57%
1580
March1st to 15thDay
45%3442435%7%53%
1828
16th to endDay
5%8%2432446%8%50%
2209
April1st to 15thDay
7%6%2432345%7%50%
2150
16th to endDay
9%8%24325%5%6%7%45%
2160
May1st to 15thDay
9%7%35%5%25%5%6%7%41%
2319
16th to endDay
8%4245%36%6%6%8%43%
2616
June1st to 15thDay
6%313325%5%8%9%49%
2520
16th to endDay
3213335%5%7%10%54%
2520
July1st to 15thDay
7%413435%6%8%9%44%
2520
16th to endDay
5%3245%46%6%7%10%44%
2632
August1st to 15thDay
6%3245%36%5%7%9%44%
2262
16th to endDay
5%214335%5%8%10%50%
2292
September1st to 15thDay
6%31333445%7%53%
2160
16th to endDay
4213323246%64%
1940
October1st to 15thDay
6%313313347%61%
1676
16th to endDay
5%5%13212245%65%
1712
November1st to 15thDay
1413324348%60%
1583
16th to endDay
2423312348%62%
1584
December1st to 15thDay
26%25%32345%7%55%
1440
16th to endDay
35%36%33435%7%54%
1536
January1st to 15thNight
1424422347%63%
2506
16th to endNight
15%35%32433460%
2541
February1st to 15thNight
27%35%333437%53%
2216
16th to endNight
17%3442325%6%57%
1894
March1st to 15thNight
45%233235%5%6%56%
2130
16th to endNight
5%6%23323348%56%
2013
April1st to 15thNight
5%7%23423347%54%
1798
16th to endNight
14%7%24323346%48%
1800
May1st to 15thNight
13%6%1442436%8%43%
1627
16th to endNight
6%5%2442345%9%50%
1497
June1st to 15thNight
421231445%11%58%
1440
16th to endNight
2223235%7%9%59%
1440
July1st to 15thNight
5%3245%36%5%7%7%48%
1440
16th to endNight
5%224425%6%8%10%46%
1533
August1st to 15thNight
5%415%435%6%6%9%47%
1698
16th to endNight
5%313325%5%6%10%52%
1910
September1st to 15thNight
6%41432446%9%52%
1800
16th to endNight
4213323345%65%
1878
October1st to 15thNight
6%5%1332335%6%58%
1952
16th to endNight
4412212347%63%
2148
November1st to 15thNight
2314323346%64%
2275
16th to endNight
35%23312337%63%
2373
December1st to 15thNight
26%25%323347%57%
2520
16th to endNight
27%36%324347%53%
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
22%411%31%24%5%
1433
16th to endDay
22%310%31%22%8%
1692
February1st to 15thDay
29%413%34%14%4
1634
16th to endDay
25%5%8%28%25%6%
1580
March1st to 15thDay
28%410%24%22%8%
1828
16th to endDay
31%5%12%24%20%5%
2211
April1st to 15thDay
32%5%11%24%19%7%
2150
16th to endDay
35%7%12%22%16%4
2160
May1st to 15thDay
40%8%11%21%15%2
2319
16th to endDay
34%9%13%23%12%6%
2620
June1st to 15thDay
28%7%14%20%17%11%
2520
16th to endDay
22%6%11%20%27%11%
2520
July1st to 15thDay
32%9%12%18%16%10%
2371
16th to endDay
33%8%13%23%15%5%
2467
August1st to 15thDay
32%9%13%18%15%9%
2247
16th to endDay
26%7%11%23%24%6%
2292
September1st to 15thDay
28%5%10%22%20%12%
2160
16th to endDay
20%47%23%35%9%
1940
October1st to 15thDay
23%411%21%29%8%
1676
16th to endDay
21%28%27%29%10%
1712
November1st to 15thDay
21%410%23%25%14%
1583
16th to endDay
20%37%23%32%12%
1584
December1st to 15thDay
26%413%28%21%4
1440
16th to endDay
28%5%14%24%19%6%
1536
January1st to 15thNight
21%412%29%26%5%
2506
16th to endNight
25%39%27%23%9%
2541
February1st to 15thNight
29%5%12%30%17%4
2226
16th to endNight
26%28%30%23%8%
1894
March1st to 15thNight
25%5%10%24%26%6%
2130
16th to endNight
27%412%25%25%5%
2013
April1st to 15thNight
28%6%11%26%19%7%
1798
16th to endNight
36%5%11%25%16%4
1800
May1st to 15thNight
37%7%13%22%13%4
1628
16th to endNight
30%9%19%23%11%6%
1498
June1st to 15thNight
21%6%18%26%14%11%
1440
16th to endNight
19%7%12%24%26%10%
1440
July1st to 15thNight
31%8%16%20%13%8%
1360
16th to endNight
28%9%17%24%18%2
1436
August1st to 15thNight
30%9%15%23%13%6%
1689
16th to endNight
25%7%12%28%19%5%
1910
September1st to 15thNight
26%6%13%22%20%10%
1800
16th to endNight
20%410%26%30%7%
1878
October1st to 15thNight
25%5%13%20%26%9%
1952
16th to endNight
20%48%27%29%10%
2148
November1st to 15thNight
20%39%24%27%14%
2275
16th to endNight
21%38%24%31%10%
2373
December1st to 15thNight
25%414%30%19%5%
2520
16th to endNight
30%5%14%24%21%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
13%8%13%36%25%2
90
16th to endDay
46%30%42%16%
96
February1st to 15thDay
28%53%28%6%
90
16th to endDay
412%37%24%20%
81
March1st to 15thDay
213%40%34%6%1
118
16th to endDay
15%24%33%19%5%1
288
April1st to 15thDay
15%20%34%20%5%2
269
16th to endDay
19%23%31%18%5%
270
May1st to 15thDay
15%9%30%28%12%3
429
16th to endDay
15%11%24%25%17%5%
517
June1st to 15thDay
9%7%26%28%20%7%
495
16th to endDay
45%25%31%25%7%
495
July1st to 15thDay
10%218%28%29%11%
475
16th to endDay
10%216%27%33%9%
491
August1st to 15thDay
10%324%34%19%7%
315
16th to endDay
7%128%35%19%6%
332
September1st to 15thDay
8%5%33%27%16%8%
315
16th to endDay
6%6%29%24%23%10%
150
October1st to 15thDay
6%324%31%20%14%
90
16th to endDay
9%329%28%22%7%
96
November1st to 15thDay
25%16%38%26%10%
90
16th to endDay
6%11%36%34%10%1
90
December1st to 15thDay
6%11%47%26%7%
90
16th to endDay
37%39%40%7%2
96
January1st to 15thNight
3434%42%12%2
900
16th to endNight
3336%45%10%1
813
February1st to 15thNight
5%437%44%7%
704
16th to endNight
5%6%45%36%7%
632
March1st to 15thNight
5%439%39%9%1
720
16th to endNight
7%7%38%38%7%
669
April1st to 15thNight
10%9%41%30%7%
539
16th to endNight
18%6%32%31%10%
540
May1st to 15thNight
15%428%39%11%
540
16th to endNight
9%333%35%15%1
563
June1st to 15thNight
5%225%45%19%1
540
16th to endNight
3122%47%24%1
540
July1st to 15thNight
7%16%39%31%4
510
16th to endNight
5%113%40%36%2
564
August1st to 15thNight
7%14%44%30%2
539
16th to endNight
6%116%45%26%4
573
September1st to 15thNight
8%217%41%25%4
540
16th to endNight
4122%42%25%2
519
October1st to 15thNight
8%429%38%15%2
632
16th to endNight
6%223%41%21%4
740
November1st to 15thNight
35%29%43%16%1
875
16th to endNight
5%431%43%13%1
900
December1st to 15thNight
4436%44%10%
900
16th to endNight
5%439%38%9%1
960
Page generated at 2017-09-25 07:02:24. Version ac04

Copyright 2017 A. Danko


Whispering Pines Observatory Clear Sky Chart | Charts Home