Woodland Trails
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woodland Trails clear sky chart from 2005-11-05 to 2018-03-21.

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
30%
15534
14%
49142
8%
15498
37%
15498
17%
34602

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
14%
779
10%
2696
2%
776
23%
776
8%
2117
January16th to endNight
16%
832
10%
2704
3%
832
24%
832
9%
2138
February1st to 15thNight
13%
761
10%
2482
2%
761
23%
761
10%
1934
February16th to endNight
16%
683
12%
2187
4%
683
26%
683
12%
1617
March1st to 15thNight
20%
780
13%
2145
5%
780
28%
780
15%
1619
March16th to endNight
27%
792
21%
2178
9%
792
37%
792
23%
1474
April1st to 15thNight
21%
718
15%
1814
4%
718
28%
718
20%
1331
April16th to endNight
32%
564
19%
1644
8%
564
40%
564
25%
1083
May1st to 15thNight
42%
477
17%
1557
11%
477
49%
477
21%
1024
May16th to endNight
42%
374
17%
1497
14%
374
53%
374
25%
828
June1st to 15thNight
38%
360
12%
1440
11%
360
47%
360
19%
864
June16th to endNight
46%
360
12%
1338
14%
360
52%
360
25%
794
July1st to 15thNight
57%
340
16%
1336
20%
340
64%
340
33%
690
July16th to endNight
56%
472
16%
1506
15%
442
60%
442
30%
874
August1st to 15thNight
58%
539
17%
1609
12%
536
62%
536
36%
949
August16th to endNight
55%
626
23%
1772
13%
626
61%
626
35%
1060
September1st to 15thNight
48%
720
20%
1803
9%
720
53%
720
34%
1172
September16th to endNight
52%
717
23%
2008
16%
717
56%
717
32%
1255
October1st to 15thNight
36%
720
16%
2160
12%
720
42%
720
20%
1498
October16th to endNight
21%
768
13%
2304
5%
768
31%
768
14%
1747
November1st to 15thNight
29%
760
17%
2590
14%
760
36%
760
17%
1808
November16th to endNight
23%
780
10%
2730
6%
780
29%
780
11%
2087
December1st to 15thNight
12%
780
6%
2730
2%
780
18%
780
7%
2221
December16th to endNight
10%
832
6%
2912
1%
832
16%
832
6%
2418

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
15%9%47%6%35%45%6%31%
49680
Night
14%9%47%6%3445%6%33%
49321
Cloud CoverDay
15%8%36%6%35%5%5%7%31%
49690
Night
15%8%36%5%35%45%6%34%
49325
TransparencyDay
50%7%11%18%10%
49377
Night
49%7%11%19%11%1
49142
SeeingDay
18%11%30%22%11%5%
6005
Night
20%11%31%25%10%1
15539

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%14%5%9%7%445%45%21%
1569
16th to endDay
14%14%6%11%7%46%5%5%5%17%
1872
February1st to 15thDay
14%15%7%11%8%45%345%19%
1710
16th to endDay
16%14%6%8%7%2445%425%
1568
March1st to 15thDay
13%13%48%8%45%34427%
2134
16th to endDay
15%8%46%5%33445%37%
2174
April1st to 15thDay
21%9%46%5%2435%5%29%
2134
16th to endDay
17%8%35%5%23446%38%
2325
May1st to 15thDay
15%7%36%6%35%45%7%34%
2392
16th to endDay
13%6%26%6%3445%7%39%
2618
June1st to 15thDay
17%6%35%5%35%5%5%8%34%
2520
16th to endDay
14%5%25%6%35%5%6%9%35%
2611
July1st to 15thDay
9%426%436%5%6%9%39%
2535
16th to endDay
10%5%27%6%36%6%7%9%34%
2556
August1st to 15thDay
9%5%37%6%35%5%6%8%37%
2340
16th to endDay
12%6%25%5%345%6%8%37%
2417
September1st to 15thDay
15%5%25%5%35%45%6%39%
2155
16th to endDay
14%5%36%5%3445%6%40%
1950
October1st to 15thDay
21%7%37%6%34345%32%
1800
16th to endDay
23%12%5%8%5%3445%5%22%
1920
November1st to 15thDay
15%11%38%7%245%47%28%
1596
16th to endDay
18%12%5%9%7%445%45%20%
1560
December1st to 15thDay
16%16%6%11%8%35%5%5%5%14%
1560
16th to endDay
19%13%6%10%7%35%5%47%15%
1664
January1st to 15thNight
18%14%5%9%6%3445%5%20%
2696
16th to endNight
13%13%6%10%8%46%5%5%6%20%
2704
February1st to 15thNight
13%15%6%8%7%36%5%5%5%21%
2480
16th to endNight
14%11%49%6%45%46%5%27%
2187
March1st to 15thNight
15%11%5%7%7%35%33431%
2133
16th to endNight
13%7%46%4245%45%42%
2178
April1st to 15thNight
19%8%35%435%345%34%
1814
16th to endNight
12%8%37%42335%6%42%
1644
May1st to 15thNight
16%425%5%345%6%7%38%
1557
16th to endNight
12%41442445%7%49%
1495
June1st to 15thNight
12%6%25%5%25%5%5%7%40%
1440
16th to endNight
11%425%5%3445%9%43%
1338
July1st to 15thNight
6%414425%446%55%
1416
16th to endNight
6%4245%345%6%8%48%
1610
August1st to 15thNight
6%5%1442447%9%49%
1620
16th to endNight
7%5%2443445%6%52%
1772
September1st to 15thNight
13%42442435%7%46%
1803
16th to endNight
12%5%3442335%6%47%
2008
October1st to 15thNight
17%7%27%5%2345%6%37%
2160
16th to endNight
21%9%26%6%35%5%5%6%27%
2304
November1st to 15thNight
18%9%36%5%345%46%33%
2590
16th to endNight
18%11%48%5%35%5%5%6%24%
2730
December1st to 15thNight
18%14%5%9%8%46%5%45%17%
2730
16th to endNight
19%13%6%10%8%35%45%5%15%
2912

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
17%14%48%7%35%445%22%
1569
16th to endDay
13%14%7%10%8%46%5%5%5%18%
1872
February1st to 15thDay
14%16%7%9%8%44345%20%
1710
16th to endDay
17%14%5%8%5%34445%26%
1568
March1st to 15thDay
14%11%5%7%7%5%5%445%27%
2145
16th to endDay
15%8%45%5%24445%37%
2173
April1st to 15thDay
21%9%45%5%3445%5%29%
2134
16th to endDay
17%7%25%5%24446%37%
2325
May1st to 15thDay
15%6%37%6%345%5%7%34%
2392
16th to endDay
13%5%26%5%345%6%7%39%
2618
June1st to 15thDay
16%5%345%36%5%5%8%34%
2520
16th to endDay
13%5%25%5%36%5%6%9%35%
2611
July1st to 15thDay
9%5%25%5%46%5%7%9%40%
2535
16th to endDay
10%5%36%6%36%5%7%9%34%
2556
August1st to 15thDay
9%5%25%6%45%6%6%9%37%
2340
16th to endDay
12%6%25%5%35%5%6%8%38%
2417
September1st to 15thDay
14%5%25%4345%6%7%38%
2155
16th to endDay
13%6%36%435%46%6%40%
1950
October1st to 15thDay
21%7%36%6%34435%33%
1800
16th to endDay
23%11%47%5%2445%5%23%
1920
November1st to 15thDay
16%10%47%6%345%5%7%28%
1596
16th to endDay
18%12%48%7%46%5%5%6%20%
1560
December1st to 15thDay
17%15%5%10%8%35%5%5%6%16%
1560
16th to endDay
19%12%6%9%7%35%5%47%17%
1664
January1st to 15thNight
20%13%5%7%6%34447%21%
2696
16th to endNight
13%13%6%9%7%46%5%46%21%
2704
February1st to 15thNight
13%14%5%9%7%35%5%5%6%23%
2473
16th to endNight
14%11%48%6%445%5%6%28%
2187
March1st to 15thNight
16%11%48%6%3433432%
2145
16th to endNight
13%7%45%425%445%42%
2178
April1st to 15thNight
19%8%25%5%35%346%34%
1814
16th to endNight
12%7%35%5%3345%6%42%
1644
May1st to 15thNight
15%4345%35%46%8%37%
1556
16th to endNight
12%414325%45%7%49%
1495
June1st to 15thNight
12%6%25%5%25%45%8%40%
1440
16th to endNight
11%5%25%5%3445%9%43%
1338
July1st to 15thNight
6%3233245%5%7%54%
1416
16th to endNight
6%4235%35%5%6%8%48%
1610
August1st to 15thNight
6%4145%2445%10%49%
1620
16th to endNight
7%424435%45%6%52%
1772
September1st to 15thNight
13%41442445%7%46%
1803
16th to endNight
12%5%25%42346%6%48%
2008
October1st to 15thNight
17%7%27%5%245%36%37%
2160
16th to endNight
21%7%36%6%35%5%5%6%28%
2304
November1st to 15thNight
18%8%25%6%3445%7%33%
2590
16th to endNight
19%10%47%5%35%45%6%25%
2730
December1st to 15thNight
18%14%5%8%7%35%5%5%6%18%
2730
16th to endNight
20%12%6%9%7%46%5%46%16%
2912

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
62%7%9%12%7%
1570
16th to endDay
65%7%9%10%6%
1872
February1st to 15thDay
65%7%8%14%3
1712
16th to endDay
59%7%9%14%7%1
1568
March1st to 15thDay
58%6%10%15%7%
2145
16th to endDay
47%6%9%18%16%1
2174
April1st to 15thDay
54%5%10%17%11%
2134
16th to endDay
46%6%10%20%15%1
2325
May1st to 15thDay
47%6%9%21%13%
2392
16th to endDay
42%7%12%21%13%1
2622
June1st to 15thDay
45%7%12%21%12%
2520
16th to endDay
43%8%13%20%13%
2611
July1st to 15thDay
38%8%12%23%15%1
2386
16th to endDay
43%8%14%21%10%1
2397
August1st to 15thDay
40%9%13%19%13%1
2327
16th to endDay
41%7%13%25%11%1
2417
September1st to 15thDay
41%8%14%23%11%
2155
16th to endDay
43%7%10%28%10%
1950
October1st to 15thDay
53%5%9%20%9%1
1800
16th to endDay
60%8%13%12%4
1920
November1st to 15thDay
53%8%12%17%7%1
1596
16th to endDay
60%9%13%11%4
1560
December1st to 15thDay
65%9%11%9%2
1560
16th to endDay
66%9%9%10%4
1664
January1st to 15thNight
63%6%10%11%7%
2696
16th to endNight
60%9%9%14%4
2704
February1st to 15thNight
59%8%9%16%5%
2482
16th to endNight
54%7%12%17%7%
2187
March1st to 15thNight
56%5%10%19%7%
2145
16th to endNight
43%6%9%22%16%1
2178
April1st to 15thNight
51%310%18%14%
1814
16th to endNight
41%6%10%20%17%3
1644
May1st to 15thNight
43%7%10%21%15%2
1557
16th to endNight
34%6%14%26%15%2
1497
June1st to 15thNight
40%6%10%25%15%1
1440
16th to endNight
37%6%13%23%17%1
1338
July1st to 15thNight
27%6%11%28%23%1
1336
16th to endNight
32%7%12%27%16%2
1506
August1st to 15thNight
30%6%18%28%14%1
1609
16th to endNight
31%6%11%32%16%1
1772
September1st to 15thNight
35%6%15%26%15%1
1803
16th to endNight
34%6%11%31%14%
2008
October1st to 15thNight
46%7%10%21%13%
2160
16th to endNight
54%8%12%15%7%
2304
November1st to 15thNight
50%6%11%18%11%1
2590
16th to endNight
57%9%14%13%4
2730
December1st to 15thNight
64%9%10%11%3
2730
16th to endNight
67%9%9%8%5%
2912

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
22%23%31%17%5%
95
16th to endDay
32%20%34%11%2
144
February1st to 15thDay
22%25%42%8%
135
16th to endDay
27%22%38%9%2
133
March1st to 15thDay
22%18%33%20%4
330
16th to endDay
21%15%36%18%6%2
311
April1st to 15thDay
24%16%34%15%7%1
270
16th to endDay
20%14%34%17%9%4
270
May1st to 15thDay
19%12%27%24%9%6%
288
16th to endDay
17%11%30%24%12%2
331
June1st to 15thDay
20%11%25%29%10%1
315
16th to endDay
16%7%33%29%10%2
406
July1st to 15thDay
11%5%25%32%17%6%
320
16th to endDay
9%7%28%31%14%8%
326
August1st to 15thDay
11%5%25%28%16%12%
313
16th to endDay
13%325%25%18%13%
332
September1st to 15thDay
10%6%23%24%22%12%
315
16th to endDay
14%5%21%25%20%13%
314
October1st to 15thDay
22%8%29%20%13%5%
315
16th to endDay
28%16%32%16%6%
336
November1st to 15thDay
23%14%29%21%9%2
130
16th to endDay
27%23%32%12%4
90
December1st to 15thDay
21%22%31%20%5%
90
16th to endDay
29%18%40%11%
96
January1st to 15thNight
27%18%33%14%4
780
16th to endNight
21%12%38%21%5%
832
February1st to 15thNight
21%17%39%18%2
764
16th to endNight
21%16%38%20%4
683
March1st to 15thNight
23%16%34%20%4
780
16th to endNight
18%13%36%22%7%1
792
April1st to 15thNight
23%14%36%20%4
718
16th to endNight
17%14%31%26%8%
564
May1st to 15thNight
18%6%27%33%12%1
477
16th to endNight
12%6%33%29%17%1
375
June1st to 15thNight
15%8%30%33%12%
360
16th to endNight
13%430%37%13%
360
July1st to 15thNight
9%325%42%18%1
340
16th to endNight
8%326%40%18%2
472
August1st to 15thNight
8%221%39%26%2
539
16th to endNight
10%324%34%23%3
626
September1st to 15thNight
15%5%25%27%21%4
720
16th to endNight
15%5%19%32%20%5%
717
October1st to 15thNight
22%8%27%26%12%1
720
16th to endNight
25%13%32%22%5%
768
November1st to 15thNight
23%11%31%22%10%1
760
16th to endNight
25%15%29%22%6%
780
December1st to 15thNight
28%15%37%15%3
780
16th to endNight
28%13%39%16%1
832
Page generated at 2018-03-22 11:34:26. Version ac04

Copyright 2018 A. Danko


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