Battle River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Battle River clear sky chart from 2005-11-06 to 2024-03-28.

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%
23933
11%
81211
7%
23873
44%
23873
18%
55156

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
35%
938
8%
4701
4%
926
39%
926
9%
3425
January11th to 20thNight
30%
938
15%
4614
7%
930
37%
930
11%
3070
January21st to endNight
25%
1028
8%
5149
4%
1019
31%
1019
9%
3362
February1st to 10thNight
37%
760
10%
2599
8%
760
43%
760
15%
1887
February11th to 20thNight
37%
740
13%
2402
9%
740
43%
740
18%
1719
February21st to endNight
46%
628
14%
2041
13%
628
50%
628
19%
1420
March1st to 10thNight
38%
760
12%
2260
9%
760
41%
760
17%
1679
March11th to 20thNight
38%
760
16%
2090
10%
760
43%
760
22%
1481
March21st to endNight
39%
820
9%
2255
5%
820
42%
820
19%
1698
April1st to 10thNight
44%
554
15%
1716
9%
554
49%
554
24%
1115
April11th to 20thNight
37%
533
13%
1601
9%
533
41%
533
19%
1146
April21st to endNight
41%
540
12%
1576
10%
540
44%
540
22%
1074
May1st to 10thNight
42%
517
9%
1417
6%
517
44%
517
22%
1006
May11th to 20thNight
51%
354
8%
1239
7%
354
53%
354
24%
766
May21st to endNight
46%
388
1%
1358
1%
388
47%
388
18%
922
June1st to 10thNight
43%
360
0%
1260
0%
360
43%
360
18%
857
June11th to 20thNight
40%
360
0%
1260
0%
360
40%
360
13%
910
June21st to endNight
54%
360
0%
1260
0%
360
54%
360
21%
797
July1st to 10thNight
60%
350
0%
1225
0%
350
60%
350
27%
715
July11th to 20thNight
57%
348
0%
1218
0%
348
57%
348
24%
746
July21st to endNight
61%
394
7%
1302
7%
372
62%
372
33%
704
August1st to 10thNight
60%
388
8%
1287
8%
386
63%
386
24%
803
August11th to 20thNight
58%
534
10%
1602
10%
534
60%
534
29%
1022
August21st to endNight
57%
594
20%
1782
16%
594
61%
594
33%
1077
September1st to 10thNight
51%
540
14%
1714
11%
540
54%
540
28%
1058
September11th to 20thNight
56%
652
18%
1912
13%
652
60%
652
31%
1182
September21st to endNight
48%
720
21%
1984
13%
720
55%
720
34%
1216
October1st to 10thNight
44%
720
16%
2160
10%
720
50%
720
25%
1419
October11th to 20thNight
40%
720
19%
2198
10%
720
47%
720
26%
1428
October21st to endNight
33%
878
15%
2660
8%
878
40%
878
20%
1860
November1st to 10thNight
32%
925
13%
2590
8%
925
36%
925
16%
1961
November11th to 20thNight
30%
950
12%
2679
6%
950
35%
950
15%
2058
November21st to endNight
28%
950
10%
2850
4%
950
33%
950
17%
2088
December1st to 10thNight
32%
950
10%
2850
5%
950
37%
950
15%
2134
December11th to 20thNight
24%
950
9%
3477
4%
949
30%
949
10%
2710
December21st to endNight
33%
1032
7%
4923
5%
1026
38%
1026
13%
2641

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
10%9%48%7%46%6%6%8%33%
78096
Night
8%9%48%7%46%6%6%8%33%
81867
TransparencyDay
46%9%17%21%7%1
77798
Night
46%8%16%20%9%1
81745
SeeingDay
13%8%27%31%16%5%
14634
Night
12%6%30%35%15%2
23988

By Month

Percentage Cloud Cover NW (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
6%9%6%15%13%6%6%46%5%25%
2219
11th to 20thDay
6%7%48%9%7%10%13%9%6%23%
2199
21st to endDay
7%13%6%10%9%45%5%5%7%29%
2478
February1st to 10thDay
8%12%7%12%10%5%7%5%5%6%23%
1581
11th to 20thDay
7%12%6%12%9%5%5%5%5%8%25%
1665
21st to endDay
5%12%5%11%9%5%7%8%8%9%21%
1413
March1st to 10thDay
8%14%6%10%10%5%8%7%7%6%20%
1918
11th to 20thDay
8%10%5%8%8%345%6%9%33%
2089
21st to endDay
10%12%6%12%9%46%5%5%7%25%
2256
April1st to 10thDay
8%11%5%9%8%45%6%5%7%32%
2244
11th to 20thDay
12%11%5%9%6%35%5%5%7%31%
2310
21st to endDay
14%11%46%5%35%5%6%9%32%
2383
May1st to 10thDay
11%9%47%7%5%6%6%6%7%31%
2542
11th to 20thDay
9%7%36%6%36%5%8%8%39%
2654
21st to endDay
17%7%36%7%46%5%7%8%33%
2917
June1st to 10thDay
15%6%36%7%47%5%7%8%31%
2700
11th to 20thDay
20%9%39%8%46%6%7%7%22%
2700
21st to endDay
12%6%25%6%46%8%8%9%35%
2700
July1st to 10thDay
10%5%245%35%6%8%9%42%
2700
11th to 20thDay
11%5%35%6%46%6%7%10%37%
2700
21st to endDay
8%425%5%35%6%7%9%46%
2938
August1st to 10thDay
9%5%36%7%46%6%6%8%39%
2642
11th to 20thDay
11%5%25%5%346%7%9%43%
2299
21st to endDay
10%6%25%435%5%6%9%45%
2574
September1st to 10thDay
11%6%36%6%45%6%5%8%42%
2246
11th to 20thDay
16%8%35%5%3345%7%42%
2047
21st to endDay
10%7%25%5%35%45%8%47%
1976
October1st to 10thDay
12%10%46%6%35%5%46%38%
1800
11th to 20thDay
11%8%47%6%345%5%7%41%
1760
21st to endDay
7%11%5%9%8%45%5%6%9%31%
1677
November1st to 10thDay
13%12%5%9%9%36%5%48%26%
1488
11th to 20thDay
7%11%8%12%10%445%7%7%25%
1497
21st to endDay
6%11%8%12%7%46%5%6%9%28%
1330
December1st to 10thDay
8%12%6%9%8%5%9%8%7%6%22%
1330
11th to 20thDay
7%10%410%9%6%7%6%7%8%24%
1682
21st to endDay
48%48%7%45%45%9%42%
2442
January1st to 10thNight
5%10%6%13%10%6%7%8%7%7%21%
4726
11th to 20thNight
47%48%11%6%8%10%7%9%26%
4699
21st to endNight
6%12%6%9%7%46%5%6%7%31%
5210
February1st to 10thNight
6%10%5%11%9%48%6%7%7%26%
2599
11th to 20thNight
6%10%49%9%5%7%7%7%7%29%
2402
21st to endNight
48%5%9%9%5%7%6%6%10%30%
2041
March1st to 10thNight
8%10%5%10%9%5%7%5%5%9%26%
2260
11th to 20thNight
7%9%5%8%8%46%5%6%8%34%
2090
21st to endNight
9%11%5%9%8%45%6%6%8%29%
2255
April1st to 10thNight
7%10%46%6%45%6%6%7%40%
1716
11th to 20thNight
10%10%49%7%46%5%7%8%30%
1601
21st to endNight
14%9%48%5%4446%8%34%
1576
May1st to 10thNight
12%9%37%7%36%6%5%8%33%
1417
11th to 20thNight
9%7%35%5%46%6%6%9%40%
1239
21st to endNight
18%6%35%6%47%6%6%8%32%
1358
June1st to 10thNight
13%8%38%6%46%6%7%7%31%
1260
11th to 20thNight
18%10%48%5%45%46%8%27%
1260
21st to endNight
9%436%7%47%6%7%8%39%
1260
July1st to 10thNight
9%6%244345%6%9%46%
1260
11th to 20thNight
10%5%25%5%35%7%8%10%41%
1260
21st to endNight
7%3245%25%46%10%51%
1379
August1st to 10thNight
8%325%5%45%8%7%11%41%
1294
11th to 20thNight
11%5%26%5%345%8%9%42%
1602
21st to endNight
8%6%26%5%345%5%8%48%
1782
September1st to 10thNight
11%6%26%5%345%5%8%46%
1714
11th to 20thNight
11%6%25%44445%7%49%
1912
21st to endNight
7%6%245%3446%9%50%
1984
October1st to 10thNight
10%8%36%5%45%5%6%9%39%
2160
11th to 20thNight
8%9%47%6%345%6%7%40%
2198
21st to endNight
9%11%48%7%346%6%8%34%
2660
November1st to 10thNight
12%14%5%8%7%46%5%5%6%28%
2590
11th to 20thNight
9%9%6%13%10%5%6%5%6%6%25%
2679
21st to endNight
5%9%7%12%9%46%5%5%8%30%
2850
December1st to 10thNight
6%12%6%10%9%5%7%5%5%7%26%
2850
11th to 20thNight
7%12%6%12%12%5%6%6%6%7%21%
3510
21st to endNight
37%37%7%5%6%5%5%7%45%
5214

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
58%8%12%17%5%
2219
11th to 20thDay
50%11%13%15%9%1
2220
21st to endDay
52%9%14%19%6%
2478
February1st to 10thDay
60%6%11%17%5%
1581
11th to 20thDay
55%8%13%15%8%1
1674
21st to endDay
53%9%13%18%7%
1413
March1st to 10thDay
60%7%16%13%4
1918
11th to 20thDay
47%9%15%19%9%
2090
21st to endDay
56%10%14%16%4
2256
April1st to 10thDay
50%7%14%19%8%1
2244
11th to 20thDay
51%7%14%19%8%1
2310
21st to endDay
47%8%16%19%8%1
2383
May1st to 10thDay
49%8%13%19%9%1
2542
11th to 20thDay
39%9%13%27%11%1
2658
21st to endDay
46%10%15%19%10%
2918
June1st to 10thDay
48%9%15%20%8%1
2700
11th to 20thDay
57%10%15%14%41
2700
21st to endDay
40%12%23%19%6%1
2700
July1st to 10thDay
35%11%24%25%6%1
2626
11th to 20thDay
39%12%25%21%3
2619
21st to endDay
31%11%25%28%5%
2775
August1st to 10thDay
38%13%22%23%3
2624
11th to 20thDay
35%10%23%24%7%
2299
21st to endDay
34%9%21%30%6%1
2574
September1st to 10thDay
38%10%18%23%8%3
2246
11th to 20thDay
43%6%17%26%7%
2047
21st to endDay
34%9%17%29%9%2
1976
October1st to 10thDay
46%7%17%23%8%
1800
11th to 20thDay
43%6%17%25%9%
1760
21st to endDay
48%9%15%20%8%
1677
November1st to 10thDay
58%6%14%17%5%1
1488
11th to 20thDay
56%9%17%15%3
1497
21st to endDay
52%9%18%17%4
1330
December1st to 10thDay
56%9%14%15%6%1
1330
11th to 20thDay
54%9%17%16%5%
1684
21st to endDay
40%5%12%27%15%2
2442
January1st to 10thNight
55%11%15%14%5%1
4726
11th to 20thNight
49%7%16%17%10%1
4740
21st to endNight
50%8%15%21%6%
5210
February1st to 10thNight
54%7%15%17%8%1
2599
11th to 20thNight
50%8%15%16%11%
2403
21st to endNight
47%9%13%21%8%1
2041
March1st to 10thNight
53%8%15%17%6%
2260
11th to 20thNight
47%7%14%23%9%1
2090
21st to endNight
51%9%16%17%7%
2255
April1st to 10thNight
40%8%16%20%15%1
1716
11th to 20thNight
49%9%13%17%10%2
1601
21st to endNight
45%7%15%20%11%2
1576
May1st to 10thNight
46%9%10%24%11%1
1417
11th to 20thNight
38%9%12%27%13%2
1239
21st to endNight
47%8%15%20%8%2
1358
June1st to 10thNight
47%9%16%21%8%
1260
11th to 20thNight
53%9%15%16%7%
1260
21st to endNight
38%12%21%23%6%1
1260
July1st to 10thNight
32%10%22%26%8%1
1225
11th to 20thNight
34%12%25%22%7%1
1218
21st to endNight
27%9%26%30%8%
1302
August1st to 10thNight
34%13%24%23%6%
1287
11th to 20thNight
36%9%22%26%7%
1602
21st to endNight
33%7%16%32%12%1
1782
September1st to 10thNight
35%9%20%23%9%4
1714
11th to 20thNight
35%7%18%29%10%2
1912
21st to endNight
31%8%15%30%13%2
1984
October1st to 10thNight
40%9%16%24%9%1
2160
11th to 20thNight
40%6%16%27%10%
2198
21st to endNight
46%9%15%22%7%1
2660
November1st to 10thNight
55%7%14%16%7%1
2590
11th to 20thNight
57%7%15%15%5%1
2679
21st to endNight
51%8%19%17%5%
2850
December1st to 10thNight
56%7%13%16%7%2
2850
11th to 20thNight
59%9%15%11%6%
3507
21st to endNight
37%6%16%21%17%3
5214

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
10%5%31%33%17%3
180
11th to 20thDay
10%12%25%29%22%2
180
21st to endDay
12%11%34%31%8%4
198
February1st to 10thDay
12%11%33%29%11%4
209
11th to 20thDay
11%8%31%28%17%4
270
21st to endDay
10%5%30%32%17%5%
225
March1st to 10thDay
12%9%30%34%13%1
412
11th to 20thDay
10%8%37%29%12%5%
460
21st to endDay
14%7%31%30%15%2
491
April1st to 10thDay
12%10%36%29%9%3
420
11th to 20thDay
16%8%26%34%13%3
412
21st to endDay
18%12%29%28%12%2
463
May1st to 10thDay
14%10%25%31%16%5%
603
11th to 20thDay
10%7%26%32%18%7%
625
21st to endDay
17%8%23%28%17%7%
679
June1st to 10thDay
15%9%25%36%13%3
630
11th to 20thDay
20%10%26%26%14%4
630
21st to endDay
11%8%21%29%22%9%
630
July1st to 10thDay
10%5%19%32%26%8%
621
11th to 20thDay
12%7%25%33%16%7%
618
21st to endDay
9%323%31%26%8%
684
August1st to 10thDay
10%6%18%33%24%8%
612
11th to 20thDay
9%6%24%34%19%7%
437
21st to endDay
13%7%20%31%21%9%
495
September1st to 10thDay
15%6%35%27%14%3
450
11th to 20thDay
21%8%25%30%13%3
450
21st to endDay
15%13%25%31%12%3
446
October1st to 10thDay
14%10%24%35%15%3
270
11th to 20thDay
16%10%32%29%12%2
270
21st to endDay
10%12%38%27%10%2
297
November1st to 10thDay
19%8%29%33%10%1
270
11th to 20thDay
14%10%40%28%7%1
259
21st to endDay
5%11%40%31%9%4
180
December1st to 10thDay
11%7%33%29%15%5%
180
11th to 20thDay
10%11%36%28%15%
180
21st to endDay
8%5%33%32%17%5%
198
January1st to 10thNight
11%7%32%36%12%2
950
11th to 20thNight
10%8%35%32%13%1
950
21st to endNight
13%10%36%32%8%1
1041
February1st to 10thNight
10%8%25%39%15%3
760
11th to 20thNight
10%7%33%34%14%2
744
21st to endNight
7%425%38%21%4
628
March1st to 10thNight
11%5%31%38%14%2
760
11th to 20thNight
10%5%33%34%16%2
760
21st to endNight
12%6%31%34%14%3
820
April1st to 10thNight
10%8%28%36%15%3
554
11th to 20thNight
14%6%32%36%11%2
533
21st to endNight
16%8%26%36%13%
540
May1st to 10thNight
13%7%27%36%15%2
517
11th to 20thNight
11%5%25%38%19%2
354
21st to endNight
19%5%21%32%21%2
389
June1st to 10thNight
18%6%25%35%15%2
360
11th to 20thNight
23%5%24%28%18%2
360
21st to endNight
10%322%38%24%2
360
July1st to 10thNight
11%5%21%37%27%
350
11th to 20thNight
11%322%45%17%2
348
21st to endNight
6%5%20%41%24%4
394
August1st to 10thNight
9%319%37%25%7%
388
11th to 20thNight
12%419%41%22%2
534
21st to endNight
10%222%41%24%1
594
September1st to 10thNight
15%325%37%18%2
540
11th to 20thNight
13%5%21%43%17%1
652
21st to endNight
10%5%32%35%17%1
720
October1st to 10thNight
14%5%29%36%15%1
720
11th to 20thNight
13%5%33%35%13%2
720
21st to endNight
15%7%34%35%9%1
878
November1st to 10thNight
18%7%32%32%9%2
925
11th to 20thNight
14%7%33%32%11%3
950
21st to endNight
9%7%38%34%11%1
950
December1st to 10thNight
12%8%33%29%15%4
950
11th to 20thNight
12%9%36%30%11%1
950
21st to endNight
10%433%35%16%3
1045
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