Walnut Point State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Walnut Point State Park clear sky chart from 2005-11-05 to 2017-10-31.

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
40%
16033
20%
47354
13%
15987
47%
15987
25%
31041

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
21%
900
17%
2506
6%
895
31%
895
19%
1809
January16th to endNight
22%
960
15%
2608
5%
960
29%
960
19%
1914
February1st to 15thNight
23%
749
13%
2157
4%
746
30%
746
17%
1542
February16th to endNight
25%
631
18%
1893
7%
631
34%
631
20%
1303
March1st to 15thNight
26%
720
15%
2160
8%
720
32%
720
18%
1524
March16th to endNight
30%
627
15%
2013
10%
627
38%
627
20%
1379
April1st to 15thNight
32%
539
19%
1797
12%
539
44%
539
23%
1148
April16th to endNight
35%
540
19%
1766
13%
540
44%
540
22%
1156
May1st to 15thNight
39%
540
15%
1620
9%
540
44%
540
22%
1121
May16th to endNight
52%
563
17%
1544
12%
561
55%
561
29%
1028
June1st to 15thNight
61%
540
20%
1440
15%
540
64%
540
40%
872
June16th to endNight
58%
540
21%
1440
15%
540
62%
540
37%
893
July1st to 15thNight
67%
510
19%
1360
16%
510
68%
510
41%
809
July16th to endNight
75%
564
27%
1417
22%
531
77%
531
50%
774
August1st to 15thNight
75%
539
22%
1677
23%
536
76%
536
37%
929
August16th to endNight
72%
573
24%
1910
26%
573
75%
573
35%
1053
September1st to 15thNight
62%
552
27%
1812
27%
552
67%
552
32%
1035
September16th to endNight
62%
717
30%
1980
23%
717
65%
717
38%
1168
October1st to 15thNight
53%
720
29%
2049
22%
720
59%
720
35%
1221
October16th to endNight
33%
768
24%
2420
15%
768
44%
768
25%
1525
November1st to 15thNight
37%
700
26%
2276
17%
700
50%
700
28%
1336
November16th to endNight
31%
720
20%
2340
14%
720
39%
720
21%
1539
December1st to 15thNight
24%
861
12%
2481
6%
861
30%
861
17%
1853
December16th to endNight
19%
960
12%
2688
4%
960
26%
960
13%
2110

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%7%35%5%3445%7%39%
48401
Night
14%7%35%424446%41%
47523
Cloud CoverDay
13%7%35%5%3445%7%38%
48410
Night
14%7%35%424446%41%
47528
TransparencyDay
43%6%12%21%13%2
48087
Night
42%5%10%23%15%2
47355
SeeingDay
15%5%23%25%20%8%
6032
Night
18%7%27%29%14%1
16033

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
17%11%6%9%7%44335%26%
1432
16th to endDay
13%12%7%8%6%34335%29%
1614
February1st to 15thDay
13%10%5%10%6%3435%5%30%
1703
16th to endDay
14%12%48%6%3435%6%29%
1580
March1st to 15thDay
19%8%47%424445%32%
1790
16th to endDay
16%11%46%5%3445%5%31%
2220
April1st to 15thDay
18%6%35%43445%6%38%
2151
16th to endDay
19%7%346%23446%36%
2193
May1st to 15thDay
21%6%36%42345%7%32%
2331
16th to endDay
11%5%36%6%35%5%6%8%37%
2567
June1st to 15thDay
9%3145%35%5%6%8%45%
2520
16th to endDay
9%425%5%35%46%9%42%
2520
July1st to 15thDay
10%4244345%8%9%42%
2520
16th to endDay
5%3244345%8%11%45%
2655
August1st to 15thDay
7%424425%5%7%9%46%
2272
16th to endDay
8%424425%5%6%9%46%
2292
September1st to 15thDay
13%4245%3445%5%44%
2135
16th to endDay
11%42343445%6%50%
1980
October1st to 15thDay
15%5%245%23447%44%
1909
16th to endDay
16%7%34413336%45%
1803
November1st to 15thDay
15%5%23323346%48%
1582
16th to endDay
18%8%445%2334439%
1620
December1st to 15thDay
21%10%5%7%6%33446%27%
1476
16th to endDay
19%14%5%7%6%24336%25%
1536
January1st to 15thNight
16%10%37%6%24445%34%
2506
16th to endNight
15%11%6%8%5%34345%33%
2608
February1st to 15thNight
15%10%5%6%5%25%436%32%
2155
16th to endNight
16%9%37%5%2433438%
1893
March1st to 15thNight
18%9%45%5%24445%35%
2147
16th to endNight
16%7%36%5%2445%7%34%
2013
April1st to 15thNight
16%5%35%434436%43%
1797
16th to endNight
17%6%344245%4441%
1766
May1st to 15thNight
18%6%33434448%36%
1620
16th to endNight
10%5%24435%5%5%8%42%
1543
June1st to 15thNight
8%41433346%8%50%
1440
16th to endNight
8%4245%3347%9%47%
1440
July1st to 15thNight
8%323425%46%9%50%
1440
16th to endNight
422332346%9%57%
1513
August1st to 15thNight
5%3133345%7%10%51%
1686
16th to endNight
6%21442445%9%52%
1910
September1st to 15thNight
10%5%23423446%51%
1812
16th to endNight
9%42442345%6%52%
1980
October1st to 15thNight
12%423423346%52%
2049
16th to endNight
17%6%13413445%45%
2420
November1st to 15thNight
11%424423446%50%
2276
16th to endNight
18%8%35%424345%39%
2340
December1st to 15thNight
22%10%47%5%33345%30%
2481
16th to endNight
23%12%5%7%5%2433425%
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
18%11%5%9%7%34435%26%
1432
16th to endDay
13%13%7%8%6%35%335%29%
1614
February1st to 15thDay
13%10%410%7%34345%30%
1703
16th to endDay
14%12%48%6%35%446%29%
1580
March1st to 15thDay
20%8%47%434445%32%
1800
16th to endDay
16%10%47%5%3345%6%31%
2219
April1st to 15thDay
18%7%34424446%38%
2151
16th to endDay
19%7%25%5%24446%36%
2193
May1st to 15thDay
20%6%35%5%245%47%32%
2331
16th to endDay
11%5%35%6%25%6%6%8%37%
2567
June1st to 15thDay
8%4145%35%5%6%8%45%
2520
16th to endDay
8%425%5%45%5%6%9%42%
2520
July1st to 15thDay
10%4244245%8%10%41%
2520
16th to endDay
5%3245%345%8%11%44%
2655
August1st to 15thDay
7%424425%5%7%10%45%
2272
16th to endDay
8%4245%35%5%6%9%46%
2292
September1st to 15thDay
12%5%245%345%5%5%44%
2135
16th to endDay
10%42342345%6%50%
1980
October1st to 15thDay
15%6%235%23446%44%
1909
16th to endDay
16%7%34322336%45%
1803
November1st to 15thDay
15%5%23423346%48%
1582
16th to endDay
18%8%445%3334439%
1620
December1st to 15thDay
21%10%5%8%5%33446%26%
1476
16th to endDay
20%13%5%7%5%25%336%25%
1536
January1st to 15thNight
16%9%47%6%24345%34%
2506
16th to endNight
15%11%5%8%5%24345%32%
2608
February1st to 15thNight
15%10%47%5%35%336%32%
2148
16th to endNight
16%8%37%5%24335%38%
1893
March1st to 15thNight
19%9%45%434435%35%
2160
16th to endNight
16%7%46%5%3435%8%34%
2013
April1st to 15thNight
15%6%35%423436%43%
1797
16th to endNight
17%7%25%4345%4441%
1766
May1st to 15thNight
18%6%3443445%8%36%
1619
16th to endNight
9%5%25%446%5%5%9%42%
1543
June1st to 15thNight
8%42432445%8%50%
1440
16th to endNight
8%4245%3446%9%47%
1440
July1st to 15thNight
8%3235%2446%10%50%
1440
16th to endNight
422332346%9%57%
1513
August1st to 15thNight
5%3233345%7%9%51%
1686
16th to endNight
6%32442445%9%52%
1910
September1st to 15thNight
10%5%14423347%51%
1812
16th to endNight
9%42432345%6%52%
1980
October1st to 15thNight
12%424422346%52%
2049
16th to endNight
17%6%23423445%45%
2420
November1st to 15thNight
11%5%24423446%50%
2276
16th to endNight
18%8%35%424345%39%
2340
December1st to 15thNight
21%11%47%5%33345%30%
2481
16th to endNight
23%12%48%5%2433425%
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
61%48%17%8%
1433
16th to endDay
57%412%18%6%
1614
February1st to 15thDay
55%412%18%8%
1705
16th to endDay
55%412%21%6%
1580
March1st to 15thDay
54%5%11%20%6%
1800
16th to endDay
53%5%12%22%6%
2220
April1st to 15thDay
45%6%9%24%12%
2151
16th to endDay
47%5%13%19%9%3
2193
May1st to 15thDay
50%6%13%20%9%
2331
16th to endDay
42%8%13%17%15%2
2571
June1st to 15thDay
34%7%12%24%18%2
2520
16th to endDay
36%7%14%21%16%4
2520
July1st to 15thDay
36%7%13%23%16%2
2371
16th to endDay
29%9%19%25%14%1
2488
August1st to 15thDay
31%8%15%25%16%2
2257
16th to endDay
32%8%13%25%13%6%
2292
September1st to 15thDay
38%5%10%20%19%5%
2135
16th to endDay
33%5%9%26%22%2
1980
October1st to 15thDay
39%411%25%15%2
1909
16th to endDay
41%310%25%17%1
1803
November1st to 15thDay
36%412%21%19%5%
1582
16th to endDay
47%49%23%13%1
1620
December1st to 15thDay
57%5%12%16%7%
1476
16th to endDay
60%5%10%16%5%
1536
January1st to 15thNight
51%5%8%21%12%
2506
16th to endNight
53%412%21%8%
2608
February1st to 15thNight
52%413%18%9%
2157
16th to endNight
49%312%24%9%
1893
March1st to 15thNight
51%5%10%21%10%1
2160
16th to endNight
47%6%13%22%8%1
2013
April1st to 15thNight
42%5%8%25%16%2
1797
16th to endNight
45%5%9%21%13%5%
1766
May1st to 15thNight
44%8%12%22%11%1
1620
16th to endNight
38%8%14%17%17%4
1545
June1st to 15thNight
30%5%12%28%19%3
1440
16th to endNight
32%6%13%22%20%5%
1440
July1st to 15thNight
28%5%14%27%17%5%
1360
16th to endNight
22%414%34%20%2
1417
August1st to 15thNight
25%8%13%26%22%3
1677
16th to endNight
27%7%11%26%19%7%
1910
September1st to 15thNight
32%5%7%25%21%7%
1812
16th to endNight
29%6%9%24%25%4
1980
October1st to 15thNight
33%48%27%20%4
2049
16th to endNight
40%47%26%17%2
2420
November1st to 15thNight
34%5%8%23%21%6%
2276
16th to endNight
46%310%23%15%
2340
December1st to 15thNight
56%410%17%10%
2481
16th to endNight
62%49%15%7%
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
30%16%28%16%7%
90
16th to endDay
9%23%40%21%4
96
February1st to 15thDay
17%18%42%17%3
90
16th to endDay
13%16%37%27%32
81
March1st to 15thDay
31%15%32%17%3
90
16th to endDay
20%15%35%19%7%
246
April1st to 15thDay
19%13%31%22%12%1
270
16th to endDay
25%6%30%21%11%5%
270
May1st to 15thDay
22%10%27%24%11%3
288
16th to endDay
14%431%25%15%8%
467
June1st to 15thDay
11%221%31%24%8%
495
16th to endDay
12%430%29%15%7%
495
July1st to 15thDay
14%119%30%22%12%
475
16th to endDay
5%112%33%32%16%
515
August1st to 15thDay
10%19%19%41%18%
349
16th to endDay
8%13%28%36%13%
332
September1st to 15thDay
14%213%25%31%13%
315
16th to endDay
12%114%27%26%17%
314
October1st to 15thDay
20%320%23%23%8%
244
16th to endDay
25%5%31%27%10%
144
November1st to 15thDay
8%11%16%30%23%10%
90
16th to endDay
33%17%25%13%8%1
90
December1st to 15thDay
18%11%34%24%10%1
90
16th to endDay
29%11%43%11%4
96
January1st to 15thNight
20%14%37%24%3
900
16th to endNight
21%14%35%24%3
960
February1st to 15thNight
20%12%36%26%3
749
16th to endNight
22%10%37%27%2
631
March1st to 15thNight
25%10%34%24%5%
720
16th to endNight
20%9%34%26%8%
627
April1st to 15thNight
20%11%31%26%9%
539
16th to endNight
21%6%33%26%11%
540
May1st to 15thNight
20%5%28%33%10%1
540
16th to endNight
11%328%31%22%1
563
June1st to 15thNight
10%121%45%21%
540
16th to endNight
9%221%43%22%
540
July1st to 15thNight
9%16%39%32%1
510
16th to endNight
5%110%40%36%5%
564
August1st to 15thNight
8%9%40%35%5%
539
16th to endNight
7%11%34%41%4
573
September1st to 15thNight
12%215%34%29%5%
552
16th to endNight
10%315%31%32%6%
717
October1st to 15thNight
14%5%21%35%19%3
720
16th to endNight
21%9%33%25%9%
768
November1st to 15thNight
14%9%34%28%13%
700
16th to endNight
23%11%30%25%8%
720
December1st to 15thNight
27%9%33%23%5%
861
16th to endNight
29%11%32%22%4
960
Page generated at 2017-11-01 16:23:39. Version ac04

Copyright 2017 A. Danko


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