White River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White River clear sky chart from 2005-11-06 to 2024-02-05.

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
24%
24061
10%
80762
5%
23958
30%
23958
12%
61967

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
16%
946
6%
4663
3%
926
20%
926
4%
3893
January11th to 20thNight
20%
943
8%
4393
5%
930
23%
930
6%
3388
January21st to endNight
20%
1037
5%
4878
3%
1023
25%
1023
6%
4199
February1st to 10thNight
24%
923
9%
2583
3%
923
29%
923
14%
1987
February11th to 20thNight
21%
703
12%
2191
6%
700
27%
700
12%
1701
February21st to endNight
18%
592
13%
1776
5%
592
25%
592
11%
1385
March1st to 10thNight
23%
720
16%
2160
7%
720
31%
720
17%
1545
March11th to 20thNight
20%
720
15%
2041
6%
720
28%
720
16%
1506
March21st to endNight
25%
716
18%
2102
9%
716
34%
716
18%
1508
April1st to 10thNight
25%
540
10%
1800
5%
540
30%
540
13%
1323
April11th to 20thNight
26%
533
16%
1625
8%
533
34%
533
16%
1173
April21st to endNight
32%
540
14%
1620
8%
540
38%
540
19%
1148
May1st to 10thNight
32%
540
11%
1566
7%
540
36%
540
17%
1157
May11th to 20thNight
27%
494
15%
1379
7%
494
36%
494
20%
991
May21st to endNight
28%
389
11%
1358
7%
388
35%
388
20%
901
June1st to 10thNight
32%
360
8%
1260
6%
360
35%
360
18%
831
June11th to 20thNight
30%
360
8%
1260
5%
360
34%
360
19%
821
June21st to endNight
37%
360
6%
1260
6%
360
39%
360
20%
829
July1st to 10thNight
40%
350
10%
1225
6%
350
45%
350
26%
732
July11th to 20thNight
39%
429
11%
1299
6%
429
41%
429
25%
856
July21st to endNight
40%
591
11%
1487
7%
558
43%
558
30%
979
August1st to 10thNight
46%
537
13%
1423
8%
534
50%
534
28%
944
August11th to 20thNight
50%
534
15%
1585
9%
534
56%
534
29%
992
August21st to endNight
39%
594
17%
1795
12%
594
43%
594
26%
1154
September1st to 10thNight
38%
540
15%
1800
9%
540
45%
540
22%
1160
September11th to 20thNight
29%
706
13%
1966
6%
706
35%
706
19%
1422
September21st to endNight
29%
720
12%
1980
7%
720
32%
720
18%
1464
October1st to 10thNight
26%
720
12%
2007
7%
720
31%
720
15%
1526
October11th to 20thNight
20%
720
9%
2314
4%
720
26%
720
11%
1824
October21st to endNight
19%
792
6%
2574
4%
792
23%
792
8%
2130
November1st to 10thNight
15%
740
10%
2406
6%
740
22%
740
8%
1955
November11th to 20thNight
13%
782
7%
2637
4%
782
17%
782
5%
2256
November21st to endNight
13%
950
4%
2850
2%
950
15%
950
5%
2511
December1st to 10thNight
15%
950
7%
2850
2%
950
20%
950
7%
2427
December11th to 20thNight
14%
950
9%
3469
3%
948
19%
948
7%
2809
December21st to endNight
15%
1040
4%
5180
3%
1026
18%
1026
3%
4540

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
16%13%5%8%7%45%5%5%6%27%
77787
Night
14%14%6%10%7%45%5%5%6%24%
81104
TransparencyDay
57%6%11%17%8%1
77481
Night
60%6%10%16%7%1
80945
SeeingDay
23%16%33%19%7%2
14530
Night
22%14%32%23%8%1
24085

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 10thDay
10%18%7%13%13%7%6%5%5%411%
2272
11th to 20thDay
6%12%7%13%12%8%7%5%5%6%19%
2530
21st to endDay
10%21%13%13%7%5%5%5%5%5%9%
2783
February1st to 10thDay
7%11%5%10%9%6%8%8%7%6%22%
1472
11th to 20thDay
7%16%6%11%9%6%6%45%7%22%
1653
21st to endDay
7%14%8%12%13%46%46%5%20%
1480
March1st to 10thDay
11%12%49%8%5%5%7%5%6%28%
1798
11th to 20thDay
12%14%6%10%7%45%445%30%
1918
21st to endDay
13%13%5%9%7%35%5%47%29%
2268
April1st to 10thDay
15%16%6%11%8%44345%24%
2160
11th to 20thDay
16%16%5%9%5%35%45%6%26%
2284
21st to endDay
15%14%47%5%345%5%6%33%
2340
May1st to 10thDay
17%12%5%8%6%35%5%6%6%29%
2391
11th to 20thDay
20%9%36%5%34445%35%
2514
21st to endDay
19%9%36%6%345%5%8%33%
2919
June1st to 10thDay
20%10%36%5%35%5%5%6%31%
2700
11th to 20thDay
17%8%36%5%35%6%6%7%34%
2700
21st to endDay
21%7%46%5%3445%7%34%
2700
July1st to 10thDay
17%6%246%445%5%9%38%
2700
11th to 20thDay
15%6%25%6%35%5%6%8%38%
2615
21st to endDay
17%7%36%5%35%5%6%9%35%
2743
August1st to 10thDay
18%8%37%6%35%6%6%7%31%
2507
11th to 20thDay
17%8%35%5%3445%7%39%
2316
21st to endDay
19%9%26%5%35%5%6%7%34%
2557
September1st to 10thDay
20%9%36%5%2445%6%36%
2156
11th to 20thDay
23%9%36%6%3445%7%31%
1980
21st to endDay
23%12%46%5%3436%7%27%
1980
October1st to 10thDay
20%18%5%7%5%33435%28%
1952
11th to 20thDay
21%21%6%8%6%35%448%16%
1643
21st to endDay
21%24%6%9%6%3345%5%14%
1782
November1st to 10thDay
19%19%9%9%6%34446%17%
1672
11th to 20thDay
16%22%7%14%9%45%44414%
1540
21st to endDay
16%22%9%15%8%444449%
1330
December1st to 10thDay
10%16%8%15%13%7%5%5%5%412%
1330
11th to 20thDay
10%17%6%13%13%6%46%46%15%
1671
21st to endDay
19%21%8%12%9%6%4335%9%
2431
January1st to 10thNight
8%16%10%15%10%7%8%5%5%5%10%
4680
11th to 20thNight
6%13%7%17%11%6%6%6%5%6%17%
4440
21st to endNight
9%19%11%16%9%6%6%5%5%410%
4884
February1st to 10thNight
7%14%6%10%7%6%8%7%7%7%22%
2583
11th to 20thNight
8%14%5%11%10%5%7%7%6%6%20%
2189
21st to endNight
7%16%8%10%9%6%8%5%5%7%20%
1776
March1st to 10thNight
6%11%6%11%7%5%6%5%5%7%30%
2149
11th to 20thNight
11%14%5%8%8%3445%7%31%
2040
21st to endNight
11%10%6%9%7%5%4445%34%
2102
April1st to 10thNight
16%14%6%8%5%35%5%6%7%26%
1800
11th to 20thNight
16%12%5%8%5%345%5%6%31%
1625
21st to endNight
17%13%36%4345%5%5%34%
1620
May1st to 10thNight
15%11%47%7%36%45%6%31%
1566
11th to 20thNight
19%9%46%5%25%5%6%6%34%
1379
21st to endNight
16%10%35%434448%38%
1357
June1st to 10thNight
18%8%25%5%2446%6%38%
1260
11th to 20thNight
17%7%35%5%35%5%6%7%38%
1260
21st to endNight
17%6%27%4335%6%8%38%
1260
July1st to 10thNight
12%426%425%45%8%46%
1260
11th to 20thNight
14%7%35%435%5%7%7%40%
1341
21st to endNight
17%6%245%2336%9%44%
1575
August1st to 10thNight
10%7%25%5%35%5%6%8%42%
1432
11th to 20thNight
12%5%245%35%45%7%47%
1585
21st to endNight
18%7%25%324448%43%
1795
September1st to 10thNight
17%8%35%6%34446%42%
1800
11th to 20thNight
19%10%25%5%4445%6%36%
1966
21st to endNight
24%10%35%42445%7%32%
1980
October1st to 10thNight
21%15%46%5%24446%30%
2007
11th to 20thNight
21%18%5%7%5%3445%6%21%
2314
21st to endNight
21%21%6%8%6%34445%17%
2574
November1st to 10thNight
17%17%8%11%7%3445%6%19%
2406
11th to 20thNight
19%18%7%14%9%45%33414%
2637
21st to endNight
16%19%8%13%11%5%5%43412%
2850
December1st to 10thNight
9%18%9%15%11%6%5%5%45%14%
2850
11th to 20thNight
10%17%9%11%9%5%6%5%5%5%17%
3526
21st to endNight
21%22%8%10%10%45%33410%
5236

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
73%7%8%9%3
2273
11th to 20thDay
65%49%18%4
2530
21st to endDay
75%5%7%6%6%1
2783
February1st to 10thDay
57%8%9%16%9%1
1472
11th to 20thDay
61%5%10%14%9%1
1662
21st to endDay
64%5%7%13%9%2
1480
March1st to 10thDay
56%5%9%16%12%3
1800
11th to 20thDay
56%5%10%17%10%2
1918
21st to endDay
55%5%10%17%11%2
2268
April1st to 10thDay
64%47%15%10%1
2160
11th to 20thDay
58%5%8%19%8%2
2284
21st to endDay
52%5%9%17%14%3
2340
May1st to 10thDay
53%6%12%17%9%2
2391
11th to 20thDay
50%5%8%23%12%1
2518
21st to endDay
49%7%12%20%10%2
2919
June1st to 10thDay
51%9%9%17%12%2
2700
11th to 20thDay
48%7%10%21%14%1
2700
21st to endDay
49%7%11%23%10%1
2700
July1st to 10thDay
41%8%12%27%11%
2626
11th to 20thDay
41%9%15%27%8%
2534
21st to endDay
45%8%13%24%10%
2591
August1st to 10thDay
49%9%15%20%7%1
2492
11th to 20thDay
44%7%14%27%9%
2316
21st to endDay
49%7%14%23%7%
2557
September1st to 10thDay
48%7%11%23%10%1
2156
11th to 20thDay
52%7%20%18%3
1980
21st to endDay
56%7%12%18%6%
1980
October1st to 10thDay
60%5%15%16%4
1952
11th to 20thDay
69%6%10%14%1
1643
21st to endDay
71%5%10%10%3
1782
November1st to 10thDay
69%5%10%12%4
1672
11th to 20thDay
75%5%9%7%3
1540
21st to endDay
79%5%7%7%11
1330
December1st to 10thDay
75%6%7%7%5%
1330
11th to 20thDay
69%6%10%10%5%
1671
21st to endDay
78%38%8%3
2431
January1st to 10thNight
73%6%9%10%3
4680
11th to 20thNight
66%5%9%16%4
4440
21st to endNight
75%5%6%9%4
4884
February1st to 10thNight
58%7%11%14%9%1
2583
11th to 20thNight
62%6%9%16%7%
2191
21st to endNight
63%49%14%9%1
1776
March1st to 10thNight
52%6%10%16%15%2
2160
11th to 20thNight
54%6%10%17%11%2
2041
21st to endNight
52%5%8%19%15%2
2102
April1st to 10thNight
56%6%9%16%11%1
1800
11th to 20thNight
54%49%21%10%2
1625
21st to endNight
50%6%9%18%15%3
1620
May1st to 10thNight
53%7%8%20%10%1
1566
11th to 20thNight
50%6%8%24%11%1
1380
21st to endNight
46%6%13%23%9%3
1358
June1st to 10thNight
45%7%12%21%13%1
1260
11th to 20thNight
44%7%11%22%14%1
1260
21st to endNight
43%8%14%25%9%1
1260
July1st to 10thNight
36%8%16%27%13%1
1225
11th to 20thNight
40%8%12%27%12%
1299
21st to endNight
39%7%18%25%12%
1487
August1st to 10thNight
37%9%22%24%7%
1423
11th to 20thNight
35%9%17%29%10%
1585
21st to endNight
39%8%15%28%10%
1795
September1st to 10thNight
44%6%14%25%11%1
1800
11th to 20thNight
49%8%15%23%5%
1966
21st to endNight
53%6%14%21%6%
1980
October1st to 10thNight
57%6%15%17%6%1
2007
11th to 20thNight
62%7%14%14%2
2314
21st to endNight
69%6%10%11%4
2574
November1st to 10thNight
67%6%10%12%5%
2406
11th to 20thNight
75%5%7%10%3
2637
21st to endNight
77%6%8%6%3
2850
December1st to 10thNight
72%6%7%10%5%
2850
11th to 20thNight
67%7%8%12%6%1
3525
21st to endNight
80%349%3
5236

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
19%18%43%13%5%2
198
11th to 20thDay
13%15%38%25%9%
270
21st to endDay
22%14%36%21%6%1
297
February1st to 10thDay
18%21%38%20%31
252
11th to 20thDay
17%27%37%14%5%
240
21st to endDay
19%38%33%8%21
198
March1st to 10thDay
18%20%40%19%4
240
11th to 20thDay
20%20%38%15%42
358
21st to endDay
23%17%34%19%5%1
462
April1st to 10thDay
22%17%38%19%31
420
11th to 20thDay
27%19%26%18%7%2
412
21st to endDay
24%21%28%17%8%2
420
May1st to 10thDay
26%15%32%15%9%3
474
11th to 20thDay
22%18%32%18%7%2
625
21st to endDay
26%15%33%19%6%1
679
June1st to 10thDay
26%14%34%18%6%2
630
11th to 20thDay
22%16%33%18%9%2
630
21st to endDay
23%15%28%21%10%3
630
July1st to 10thDay
19%10%39%21%8%3
621
11th to 20thDay
16%14%34%24%9%3
618
21st to endDay
19%11%32%25%10%3
684
August1st to 10thDay
21%10%31%26%10%3
626
11th to 20thDay
19%10%25%25%14%6%
452
21st to endDay
24%13%28%20%11%5%
495
September1st to 10thDay
25%12%31%18%11%3
450
11th to 20thDay
29%13%30%19%7%2
450
21st to endDay
31%12%26%20%9%1
450
October1st to 10thDay
28%18%26%20%7%1
450
11th to 20thDay
30%22%29%17%3
293
21st to endDay
32%24%30%10%3
297
November1st to 10thDay
33%16%37%13%1
270
11th to 20thDay
28%24%35%10%2
201
21st to endDay
31%22%33%11%31
180
December1st to 10thDay
22%19%33%17%8%1
180
11th to 20thDay
22%19%40%13%6%
180
21st to endDay
26%20%33%14%7%1
198
January1st to 10thNight
20%15%40%19%5%1
950
11th to 20thNight
18%17%34%22%7%1
950
21st to endNight
18%11%38%24%8%1
1045
February1st to 10thNight
15%15%38%25%6%1
923
11th to 20thNight
18%15%37%19%10%1
703
21st to endNight
18%18%37%22%5%1
592
March1st to 10thNight
14%18%38%21%8%1
720
11th to 20thNight
19%19%36%18%7%
720
21st to endNight
17%14%37%22%9%1
716
April1st to 10thNight
24%15%30%23%6%2
540
11th to 20thNight
23%16%29%24%8%1
533
21st to endNight
22%13%28%25%9%2
540
May1st to 10thNight
21%12%29%31%6%
540
11th to 20thNight
25%12%32%22%7%1
494
21st to endNight
22%11%36%27%5%
389
June1st to 10thNight
24%11%30%26%9%
360
11th to 20thNight
21%11%33%24%10%
360
21st to endNight
19%8%33%29%12%1
360
July1st to 10thNight
16%8%32%31%12%1
350
11th to 20thNight
18%9%31%31%11%1
429
21st to endNight
19%6%30%29%14%1
591
August1st to 10thNight
15%5%28%35%16%1
537
11th to 20thNight
15%427%34%18%2
534
21st to endNight
23%6%28%28%13%1
594
September1st to 10thNight
22%6%30%27%13%3
540
11th to 20thNight
27%10%31%22%8%1
706
21st to endNight
30%11%26%23%10%
720
October1st to 10thNight
32%13%24%23%8%
720
11th to 20thNight
31%13%29%20%6%1
720
21st to endNight
33%14%25%21%6%
792
November1st to 10thNight
26%18%33%19%41
740
11th to 20thNight
30%16%30%17%6%
782
21st to endNight
28%19%30%19%4
950
December1st to 10thNight
19%18%34%21%7%1
950
11th to 20thNight
19%19%37%17%7%1
950
21st to endNight
27%16%30%18%7%1
1045
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