Buffalo Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Buffalo Point clear sky chart from 2005-11-06 to 2024-01-17.

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
36%
25087
8%
74823
5%
25030
39%
25030
11%
60876

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
34%
950
5%
2837
3%
946
36%
946
6%
2473
January11th to 20thNight
29%
935
4%
2803
2%
935
30%
935
6%
2483
January21st to endNight
26%
990
6%
2773
2%
990
30%
990
8%
2386
February1st to 10thNight
34%
900
9%
2340
4%
900
36%
900
12%
1934
February11th to 20thNight
38%
876
12%
2274
6%
874
41%
874
15%
1800
February21st to endNight
34%
740
9%
1924
4%
740
37%
740
11%
1629
March1st to 10thNight
35%
622
7%
2062
4%
622
38%
622
8%
1710
March11th to 20thNight
35%
540
12%
1980
8%
540
43%
540
10%
1542
March21st to endNight
38%
594
10%
2178
9%
594
42%
594
9%
1727
April1st to 10thNight
36%
540
11%
1807
9%
540
41%
540
12%
1392
April11th to 20thNight
40%
533
12%
1599
10%
533
44%
533
12%
1271
April21st to endNight
39%
540
9%
1620
5%
540
43%
540
12%
1301
May1st to 10thNight
39%
540
9%
1487
4%
540
41%
540
14%
1167
May11th to 20thNight
41%
531
10%
1417
4%
531
44%
531
15%
1106
May21st to endNight
45%
584
9%
1375
3%
582
47%
582
17%
1097
June1st to 10thNight
47%
540
6%
1260
3%
540
49%
540
19%
994
June11th to 20thNight
45%
540
6%
1260
3%
540
47%
540
19%
991
June21st to endNight
56%
540
5%
1260
4%
540
58%
540
19%
992
July1st to 10thNight
63%
525
7%
1225
5%
525
64%
525
28%
887
July11th to 20thNight
57%
522
9%
1218
4%
522
59%
522
24%
916
July21st to endNight
63%
591
11%
1327
4%
558
63%
558
22%
1018
August1st to 10thNight
61%
537
13%
1561
6%
534
64%
534
20%
1103
August11th to 20thNight
56%
534
14%
1600
10%
534
61%
534
19%
1147
August21st to endNight
55%
594
14%
1782
14%
594
58%
594
18%
1295
September1st to 10thNight
49%
540
11%
1777
11%
540
52%
540
17%
1264
September11th to 20thNight
45%
540
13%
1910
12%
540
51%
540
15%
1383
September21st to endNight
37%
548
13%
1988
9%
548
45%
548
13%
1476
October1st to 10thNight
31%
720
10%
2160
6%
720
34%
720
12%
1701
October11th to 20thNight
28%
720
8%
2160
5%
720
31%
720
9%
1795
October21st to endNight
25%
918
5%
2537
2%
918
27%
918
8%
2184
November1st to 10thNight
25%
925
7%
2591
3%
925
29%
925
8%
2207
November11th to 20thNight
24%
950
8%
2660
4%
950
28%
950
6%
2369
November21st to endNight
18%
950
5%
2660
2%
950
22%
950
7%
2320
December1st to 10thNight
26%
950
2%
2812
0%
950
27%
950
4%
2564
December11th to 20thNight
19%
949
5%
3459
1%
949
22%
949
3%
2977
December21st to endNight
23%
1039
2%
5140
1%
1026
26%
1026
3%
4275

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%8%37%6%35%5%5%7%42%
74723
Night
10%9%48%6%345%5%6%39%
75130
TransparencyDay
31%39%10%14%5%
74407
Night
33%39%9%13%6%
74965
SeeingDay
14%10%31%28%13%3
15032
Night
15%7%32%32%13%1
25097

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
7%10%5%9%8%46%5%5%10%31%
1329
11th to 20thDay
6%13%410%8%5%7%6%5%8%28%
1302
21st to endDay
8%11%5%11%9%5%7%5%7%7%23%
1581
February1st to 10thDay
7%10%5%8%7%47%5%6%7%33%
1620
11th to 20thDay
7%10%37%7%35%5%7%8%39%
1574
21st to endDay
39%48%9%45%6%7%7%39%
1332
March1st to 10thDay
9%9%36%6%45%5%6%7%42%
1914
11th to 20thDay
8%9%38%6%35%6%5%5%42%
1978
21st to endDay
7%8%48%6%445%5%6%44%
2178
April1st to 10thDay
10%9%26%5%345%6%7%43%
2150
11th to 20thDay
12%9%36%6%35%5%6%7%39%
2312
21st to endDay
14%8%37%5%3435%7%41%
2340
May1st to 10thDay
12%7%35%5%34446%47%
2471
11th to 20thDay
12%5%25%5%35%5%5%7%45%
2479
21st to endDay
14%7%245%3445%6%47%
2897
June1st to 10thDay
11%5%25%5%345%5%8%46%
2700
11th to 20thDay
11%5%25%4245%5%7%49%
2700
21st to endDay
11%5%26%4346%7%9%44%
2700
July1st to 10thDay
6%3134345%5%8%57%
2700
11th to 20thDay
9%5%25%5%345%5%8%49%
2700
21st to endDay
6%423434448%57%
2912
August1st to 10thDay
7%424435%5%6%8%53%
2366
11th to 20thDay
10%4244345%6%8%50%
2301
21st to endDay
10%6%25%5%345%5%6%50%
2574
September1st to 10thDay
11%6%25%42445%9%48%
2182
11th to 20thDay
13%7%25%6%3445%7%43%
2048
21st to endDay
16%6%25%5%35%45%8%41%
1954
October1st to 10thDay
18%12%37%7%44446%33%
1800
11th to 20thDay
16%9%5%6%5%345%5%6%35%
1800
21st to endDay
16%15%5%10%6%35%435%29%
1814
November1st to 10thDay
13%12%5%9%7%4445%5%32%
1487
11th to 20thDay
10%14%6%12%9%5%5%44428%
1520
21st to endDay
11%13%413%11%445%35%27%
1520
December1st to 10thDay
8%12%5%13%10%47%5%6%6%24%
1367
11th to 20thDay
9%14%5%11%8%45%5%5%6%28%
1679
21st to endDay
13%13%6%10%8%5%5%5%5%425%
2442
January1st to 10thNight
5%10%410%9%5%6%7%6%7%31%
2837
11th to 20thNight
7%12%6%10%8%5%5%5%7%7%28%
2803
21st to endNight
8%13%5%9%8%46%5%6%8%28%
2773
February1st to 10thNight
6%10%49%9%46%6%6%6%35%
2340
11th to 20thNight
8%9%36%5%45%5%6%7%42%
2273
21st to endNight
5%8%410%8%46%5%6%8%39%
1924
March1st to 10thNight
8%10%48%7%445%5%6%40%
2062
11th to 20thNight
8%9%37%6%345%46%46%
1980
21st to endNight
11%9%37%43445%6%44%
2178
April1st to 10thNight
12%7%46%5%2445%6%44%
1807
11th to 20thNight
14%10%35%434445%44%
1599
21st to endNight
12%10%37%6%3435%5%41%
1620
May1st to 10thNight
13%7%36%433446%48%
1487
11th to 20thNight
15%5%2443436%7%47%
1417
21st to endNight
14%6%24424346%51%
1375
June1st to 10thNight
12%5%25%43445%7%48%
1260
11th to 20thNight
11%4245%3345%7%53%
1260
21st to endNight
8%5%2444445%7%52%
1260
July1st to 10thNight
5%31322335%8%65%
1260
11th to 20thNight
7%4134245%5%10%56%
1260
21st to endNight
6%313324347%62%
1405
August1st to 10thNight
6%42443336%7%58%
1570
11th to 20thNight
10%42243345%8%54%
1600
21st to endNight
11%5%2442435%6%55%
1782
September1st to 10thNight
12%5%234235%5%6%54%
1777
11th to 20thNight
13%6%2432436%7%50%
1910
21st to endNight
16%6%25%5%3345%6%45%
1988
October1st to 10thNight
16%11%36%5%3345%6%38%
2160
11th to 20thNight
15%11%36%5%35%447%35%
2160
21st to endNight
17%13%49%6%44446%28%
2537
November1st to 10thNight
13%12%49%6%345%45%35%
2591
11th to 20thNight
10%14%5%12%9%35%445%29%
2660
21st to endNight
11%12%5%11%9%5%5%5%45%29%
2660
December1st to 10thNight
7%11%5%14%11%5%6%5%5%6%26%
2812
11th to 20thNight
7%13%5%12%10%5%6%5%5%6%25%
3518
21st to endNight
13%14%6%11%9%4445%5%25%
5225

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
36%41%11%11%1
1329
11th to 20thDay
41%43%7%7%2
1302
21st to endDay
43%39%5%7%5%
1581
February1st to 10thDay
36%38%6%11%7%1
1620
11th to 20thDay
30%39%11%12%7%1
1583
21st to endDay
35%40%10%10%41
1332
March1st to 10thDay
37%39%10%10%5%
1914
11th to 20thDay
32%39%11%13%5%1
1980
21st to endDay
34%37%11%12%5%
2178
April1st to 10thDay
31%37%7%16%7%1
2150
11th to 20thDay
33%39%9%12%6%1
2312
21st to endDay
34%38%11%11%6%1
2340
May1st to 10thDay
32%38%9%12%7%1
2471
11th to 20thDay
28%40%9%15%7%1
2483
21st to endDay
31%39%8%11%10%1
2897
June1st to 10thDay
28%41%12%13%5%
2700
11th to 20thDay
26%39%12%17%6%
2700
21st to endDay
25%41%14%14%5%
2700
July1st to 10thDay
16%41%13%22%7%
2626
11th to 20thDay
23%41%11%20%6%
2619
21st to endDay
22%42%12%17%6%1
2750
August1st to 10thDay
24%39%13%17%7%
2351
11th to 20thDay
25%38%13%20%5%
2301
21st to endDay
21%39%12%21%7%
2574
September1st to 10thDay
24%38%11%20%7%
2182
11th to 20thDay
28%39%13%16%4
2048
21st to endDay
28%39%9%21%3
1954
October1st to 10thDay
35%39%10%13%3
1800
11th to 20thDay
38%39%8%11%3
1800
21st to endDay
40%41%9%9%1
1814
November1st to 10thDay
36%42%9%8%41
1487
11th to 20thDay
41%43%6%7%4
1520
21st to endDay
40%42%10%6%2
1520
December1st to 10thDay
41%43%9%6%1
1367
11th to 20thDay
43%35%11%10%1
1680
21st to endDay
50%28%9%11%2
2442
January1st to 10thNight
39%42%8%9%2
2837
11th to 20thNight
41%41%7%9%2
2803
21st to endNight
39%39%7%10%4
2773
February1st to 10thNight
35%37%9%12%7%
2340
11th to 20thNight
28%39%11%13%9%
2274
21st to endNight
35%39%10%10%6%
1924
March1st to 10thNight
37%38%9%10%5%1
2062
11th to 20thNight
31%38%9%14%7%
1980
21st to endNight
33%38%10%12%6%1
2178
April1st to 10thNight
30%37%7%15%9%2
1807
11th to 20thNight
32%37%7%13%10%1
1599
21st to endNight
32%38%7%14%8%1
1620
May1st to 10thNight
28%38%8%14%10%1
1487
11th to 20thNight
27%38%10%14%9%1
1417
21st to endNight
27%38%9%12%13%1
1375
June1st to 10thNight
25%38%13%15%8%1
1260
11th to 20thNight
25%38%11%17%8%1
1260
21st to endNight
24%39%14%17%5%1
1260
July1st to 10thNight
13%39%12%26%9%1
1225
11th to 20thNight
16%40%15%19%10%
1218
21st to endNight
18%41%10%19%11%1
1327
August1st to 10thNight
17%38%11%24%9%
1561
11th to 20thNight
20%37%11%24%7%
1600
21st to endNight
20%38%10%23%8%
1782
September1st to 10thNight
21%38%10%21%10%
1777
11th to 20thNight
24%37%13%20%6%
1910
21st to endNight
26%38%11%21%5%
1988
October1st to 10thNight
28%40%11%15%6%
2160
11th to 20thNight
36%39%10%13%2
2160
21st to endNight
37%41%10%10%2
2537
November1st to 10thNight
36%41%7%10%5%1
2591
11th to 20thNight
41%42%6%8%3
2660
21st to endNight
37%43%10%7%3
2660
December1st to 10thNight
43%43%8%41
2812
11th to 20thNight
46%35%8%8%3
3516
21st to endNight
50%29%9%9%3
5225

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
14%11%36%27%11%1
270
11th to 20thDay
13%9%34%36%9%
258
21st to endDay
16%6%35%29%12%2
264
February1st to 10thDay
13%12%43%27%5%1
240
11th to 20thDay
8%18%39%22%9%3
240
21st to endDay
9%16%43%21%10%2
198
March1st to 10thDay
10%12%39%28%9%2
240
11th to 20thDay
13%15%32%23%14%3
240
21st to endDay
9%14%34%30%12%1
264
April1st to 10thDay
14%14%34%25%12%1
410
11th to 20thDay
18%13%28%28%11%2
590
21st to endDay
18%7%33%30%11%1
600
May1st to 10thDay
18%11%34%26%8%3
603
11th to 20thDay
17%10%30%28%12%3
625
21st to endDay
19%8%26%32%13%2
679
June1st to 10thDay
14%9%29%29%17%3
630
11th to 20thDay
14%10%34%28%13%2
630
21st to endDay
15%8%27%29%16%6%
630
July1st to 10thDay
10%5%26%34%19%5%
621
11th to 20thDay
11%9%26%32%19%4
618
21st to endDay
7%6%26%35%19%7%
684
August1st to 10thDay
8%6%26%33%21%6%
626
11th to 20thDay
11%6%24%34%18%7%
615
21st to endDay
13%7%29%27%21%3
693
September1st to 10thDay
12%10%34%26%18%1
472
11th to 20thDay
17%13%33%25%10%1
338
21st to endDay
22%16%33%23%5%1
270
October1st to 10thDay
20%14%29%25%12%1
270
11th to 20thDay
17%14%33%31%4
270
21st to endDay
23%22%30%21%4
297
November1st to 10thDay
20%14%34%24%8%
270
11th to 20thDay
17%20%36%21%6%
270
21st to endDay
21%19%36%22%21
270
December1st to 10thDay
15%13%36%27%9%1
270
11th to 20thDay
16%17%43%21%3
270
21st to endDay
16%9%37%25%10%2
297
January1st to 10thNight
12%8%34%31%13%2
950
11th to 20thNight
15%6%33%35%10%1
935
21st to endNight
15%7%36%31%8%1
990
February1st to 10thNight
12%6%34%35%11%1
900
11th to 20thNight
13%7%34%30%12%4
879
21st to endNight
10%7%37%31%13%2
740
March1st to 10thNight
14%8%34%29%14%1
622
11th to 20thNight
11%7%38%33%9%1
540
21st to endNight
21%7%28%28%13%3
594
April1st to 10thNight
17%8%30%32%12%1
540
11th to 20thNight
19%6%30%31%14%1
533
21st to endNight
19%5%28%36%11%
540
May1st to 10thNight
18%7%29%34%11%1
540
11th to 20thNight
19%6%28%33%13%1
531
21st to endNight
19%328%37%13%
584
June1st to 10thNight
17%5%26%35%17%1
540
11th to 20thNight
16%5%29%35%14%1
540
21st to endNight
9%5%26%36%23%1
540
July1st to 10thNight
7%323%42%23%2
525
11th to 20thNight
6%5%27%39%20%2
522
21st to endNight
8%422%42%23%2
591
August1st to 10thNight
8%420%42%25%1
537
11th to 20thNight
12%5%22%35%23%3
534
21st to endNight
12%5%24%36%22%1
594
September1st to 10thNight
12%5%29%35%16%2
540
11th to 20thNight
15%7%30%31%16%1
540
21st to endNight
17%6%34%29%12%1
548
October1st to 10thNight
18%10%35%29%7%1
720
11th to 20thNight
21%9%34%28%7%1
720
21st to endNight
22%13%30%26%7%1
918
November1st to 10thNight
18%10%37%25%9%1
925
11th to 20thNight
19%10%35%28%7%1
950
21st to endNight
19%12%39%22%6%1
950
December1st to 10thNight
14%7%35%31%11%1
950
11th to 20thNight
20%9%37%26%7%1
950
21st to endNight
19%8%32%30%10%1
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