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 2025-01-07.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	11% 8% 3 8% 5% 4 5% 4 5% 7% 40%	108842
	Night	10% 10% 4 10% 6% 5% 5% 4 5% 6% 36%	108819
Transparency	Day	26% 46% 9% 13% 5%	108586
	Night	30% 45% 8% 13% 4	108722
Seeing	Day	15% 11% 32% 28% 13% 3	16410
	Night	16% 8% 32% 32% 12% 1	26426

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	5% 11% 7% 15% 6% 6% 6% 4 6% 8% 27%	2261
	11th to 20th	Day	3 9% 4 15% 10% 9% 7% 5% 6% 8% 24%	2199
	21st to end	Day	7% 13% 9% 14% 7% 6% 6% 4 6% 6% 22%	2788
February	1st to 10th	Day	7% 10% 5% 10% 6% 5% 7% 4 6% 7% 32%	1710
	11th to 20th	Day	6% 9% 3 9% 5% 5% 5% 3 7% 8% 39%	1664
	21st to end	Day	3 9% 4 9% 7% 5% 5% 4 7% 8% 39%	1413
March	1st to 10th	Day	10% 8% 2 5% 7% 6% 5% 4 5% 7% 39%	3335
	11th to 20th	Day	6% 7% 3 12% 7% 4 5% 4 6% 7% 39%	3478
	21st to end	Day	9% 14% 4 8% 4 4 4 3 5% 6% 41%	3814
April	1st to 10th	Day	9% 8% 2 6% 4 4 4 4 6% 8% 43%	2270
	11th to 20th	Day	12% 9% 3 7% 5% 4 4 4 6% 7% 38%	2442
	21st to end	Day	14% 8% 3 7% 4 4 4 3 5% 7% 41%	2470
May	1st to 10th	Day	14% 8% 3 6% 5% 4 4 3 5% 7% 42%	4363
	11th to 20th	Day	14% 6% 3 7% 4 5% 5% 4 5% 7% 39%	4399
	21st to end	Day	17% 9% 3 6% 4 3 3 3 4 6% 42%	5139
June	1st to 10th	Day	11% 5% 2 6% 4 4 4 4 5% 9% 46%	2850
	11th to 20th	Day	11% 5% 2 6% 4 3 4 4 5% 7% 48%	2850
	21st to end	Day	12% 4 2 6% 4 4 4 4 7% 9% 44%	2850
July	1st to 10th	Day	7% 3 1 4 3 4 5% 5% 7% 11% 49%	4750
	11th to 20th	Day	7% 4 2 5% 3 3 4 4 6% 9% 54%	4750
	21st to end	Day	9% 5% 2 5% 4 4 5% 3 5% 8% 49%	5099
August	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 5% 8% 48%	4170
	11th to 20th	Day	11% 4 2 5% 3 3 5% 4 6% 8% 48%	4041
	21st to end	Day	12% 6% 2 6% 3 3 4 3 5% 8% 47%	4532
September	1st to 10th	Day	11% 6% 2 6% 3 4 4 3 5% 9% 48%	2303
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 5% 7% 43%	2161
	21st to end	Day	15% 6% 2 6% 4 4 5% 3 5% 7% 42%	2062
October	1st to 10th	Day	13% 8% 2 6% 4 4 4 3 5% 6% 44%	3160
	11th to 20th	Day	13% 8% 4 7% 4 4 3 3 5% 7% 42%	3140
	21st to end	Day	14% 11% 3 10% 5% 4 5% 3 4 7% 33%	3135
November	1st to 10th	Day	13% 13% 5% 10% 6% 5% 4 3 5% 5% 32%	1567
	11th to 20th	Day	11% 14% 6% 14% 7% 5% 5% 3 4 4 29%	1600
	21st to end	Day	11% 13% 4 17% 9% 5% 4 3 3 5% 26%	1600
December	1st to 10th	Day	11% 15% 4 17% 12% 6% 5% 4 4 5% 16%	2340
	11th to 20th	Day	10% 16% 5% 12% 6% 5% 5% 4 4 5% 29%	2639
	21st to end	Day	11% 15% 8% 18% 8% 7% 5% 3 4 4 18%	3498
January	1st to 10th	Night	4 11% 5% 14% 9% 7% 7% 5% 6% 7% 25%	4828
	11th to 20th	Night	4 11% 5% 16% 10% 9% 7% 5% 7% 6% 19%	4709
	21st to end	Night	9% 17% 8% 12% 6% 5% 5% 4 4 6% 23%	4877
February	1st to 10th	Night	6% 11% 4 11% 6% 5% 6% 4 6% 6% 35%	2470
	11th to 20th	Night	7% 8% 3 9% 4 5% 6% 4 6% 7% 41%	2403
	21st to end	Night	5% 8% 3 12% 6% 5% 5% 4 5% 8% 38%	2041
March	1st to 10th	Night	10% 9% 3 9% 6% 5% 4 4 6% 6% 37%	3550
	11th to 20th	Night	5% 9% 3 11% 6% 4 5% 4 5% 8% 40%	3480
	21st to end	Night	12% 14% 4 10% 4 5% 3 3 4 5% 36%	3817
April	1st to 10th	Night	12% 7% 3 7% 5% 3 4 3 5% 6% 44%	1907
	11th to 20th	Night	14% 9% 3 6% 3 4 4 3 4 5% 43%	1689
	21st to end	Night	13% 10% 3 8% 5% 4 4 3 5% 6% 41%	1710
May	1st to 10th	Night	17% 6% 3 7% 3 4 3 3 5% 7% 43%	2605
	11th to 20th	Night	17% 6% 2 5% 3 4 4 3 5% 7% 43%	2507
	21st to end	Night	18% 6% 2 6% 4 3 4 3 4 5% 45%	2444
June	1st to 10th	Night	12% 4 2 6% 3 4 4 3 6% 7% 48%	1330
	11th to 20th	Night	12% 4 2 5% 3 4 3 3 5% 7% 52%	1330
	21st to end	Night	9% 5% 2 5% 3 5% 4 3 5% 7% 52%	1330
July	1st to 10th	Night	7% 3 1 4 3 4 4 4 7% 10% 54%	2220
	11th to 20th	Night	5% 3 1 4 3 3 4 3 4 10% 60%	2220
	21st to end	Night	9% 4 2 4 3 3 4 3 5% 9% 54%	2464
August	1st to 10th	Night	6% 4 1 5% 5% 5% 5% 4 7% 10% 47%	2767
	11th to 20th	Night	11% 4 2 4 3 4 4 4 6% 9% 52%	2798
	21st to end	Night	11% 5% 3 6% 3 3 4 3 5% 8% 49%	3135
September	1st to 10th	Night	11% 5% 2 4 3 3 4 3 5% 6% 54%	1876
	11th to 20th	Night	13% 6% 2 5% 2 3 4 3 6% 7% 49%	2017
	21st to end	Night	15% 6% 2 6% 4 3 3 3 5% 6% 46%	2099
October	1st to 10th	Night	14% 7% 2 5% 4 3 4 3 4 7% 47%	3800
	11th to 20th	Night	13% 10% 3 7% 4 4 4 3 5% 7% 40%	3779
	21st to end	Night	15% 12% 4 9% 5% 5% 4 3 4 5% 34%	4402
November	1st to 10th	Night	13% 12% 4 10% 5% 4 5% 3 4 5% 34%	2731
	11th to 20th	Night	11% 15% 5% 14% 6% 4 5% 3 4 5% 29%	2800
	21st to end	Night	11% 13% 5% 15% 7% 6% 5% 4 4 5% 27%	2800
December	1st to 10th	Night	9% 17% 7% 19% 10% 6% 5% 3 4 4 16%	4836
	11th to 20th	Night	7% 14% 5% 13% 8% 7% 6% 5% 5% 6% 24%	5568
	21st to end	Night	10% 14% 7% 19% 8% 6% 4 3 4 4 20%	7480

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	39% 40% 6% 10% 5%	2261
	11th to 20th	Day	39% 39% 10% 10% 2	2220
	21st to end	Day	40% 43% 8% 7% 2	2788
February	1st to 10th	Day	20% 66% 6% 5% 3	1710
	11th to 20th	Day	19% 64% 5% 8% 3	1673
	21st to end	Day	17% 66% 4 7% 7%	1413
March	1st to 10th	Day	28% 43% 9% 14% 6%	3335
	11th to 20th	Day	28% 43% 10% 13% 7%	3480
	21st to end	Day	31% 42% 5% 15% 6%	3814
April	1st to 10th	Day	15% 66% 4 8% 6%	2270
	11th to 20th	Day	16% 66% 4 9% 4 1	2442
	21st to end	Day	17% 65% 4 10% 3 1	2470
May	1st to 10th	Day	27% 43% 8% 16% 6%	4363
	11th to 20th	Day	31% 43% 8% 11% 7%	4403
	21st to end	Day	30% 42% 8% 17% 3	5139
June	1st to 10th	Day	13% 66% 6% 10% 5%	2850
	11th to 20th	Day	17% 65% 5% 8% 4	2850
	21st to end	Day	17% 65% 7% 10% 2	2850
July	1st to 10th	Day	23% 40% 15% 18% 3	4676
	11th to 20th	Day	17% 38% 16% 23% 6%	4669
	21st to end	Day	24% 38% 12% 22% 4	4938
August	1st to 10th	Day	22% 39% 12% 18% 9% 1	4155
	11th to 20th	Day	23% 39% 17% 18% 3	4080
	21st to end	Day	27% 38% 16% 17% 2	4531
September	1st to 10th	Day	15% 61% 8% 12% 4	2303
	11th to 20th	Day	17% 61% 9% 11% 1	2161
	21st to end	Day	21% 61% 5% 10% 3	2062
October	1st to 10th	Day	24% 37% 10% 20% 9%	3160
	11th to 20th	Day	22% 37% 10% 15% 15%	3140
	21st to end	Day	31% 38% 11% 16% 4	3135
November	1st to 10th	Day	29% 57% 6% 7% 1	1567
	11th to 20th	Day	27% 58% 8% 5% 1	1600
	21st to end	Day	30% 57% 5% 7% 1	1600
December	1st to 10th	Day	48% 38% 8% 5% 1	2340
	11th to 20th	Day	39% 33% 7% 14% 7%	2640
	21st to end	Day	55% 29% 5% 9% 2	3498
January	1st to 10th	Night	40% 40% 9% 8% 3	4828
	11th to 20th	Night	43% 39% 7% 9% 1	4750
	21st to end	Night	44% 42% 8% 5% 1	4877
February	1st to 10th	Night	20% 66% 6% 5% 4	2470
	11th to 20th	Night	18% 65% 7% 8% 2	2404
	21st to end	Night	18% 65% 4 10% 4	2041
March	1st to 10th	Night	25% 45% 10% 13% 6%	3550
	11th to 20th	Night	24% 45% 14% 12% 6%	3480
	21st to end	Night	35% 42% 4 12% 6% 1	3817
April	1st to 10th	Night	15% 65% 5% 7% 7% 1	1907
	11th to 20th	Night	16% 65% 3 7% 7% 1	1689
	21st to end	Night	17% 65% 3 11% 3 1	1710
May	1st to 10th	Night	28% 42% 6% 17% 8%	2605
	11th to 20th	Night	28% 42% 8% 15% 7%	2507
	21st to end	Night	27% 42% 7% 19% 5%	2444
June	1st to 10th	Night	14% 66% 7% 8% 5%	1330
	11th to 20th	Night	15% 65% 3 9% 7% 1	1330
	21st to end	Night	14% 65% 7% 12% 3	1330
July	1st to 10th	Night	19% 40% 19% 19% 3	2185
	11th to 20th	Night	13% 37% 14% 30% 6%	2178
	21st to end	Night	19% 37% 16% 24% 3	2386
August	1st to 10th	Night	22% 38% 13% 23% 4	2758
	11th to 20th	Night	20% 39% 18% 20% 2	2825
	21st to end	Night	25% 37% 16% 17% 4	3135
September	1st to 10th	Night	14% 61% 8% 13% 4	1876
	11th to 20th	Night	15% 62% 10% 10% 3	2017
	21st to end	Night	20% 60% 6% 9% 5%	2099
October	1st to 10th	Night	23% 37% 6% 26% 8%	3800
	11th to 20th	Night	25% 37% 10% 24% 4	3779
	21st to end	Night	34% 36% 6% 19% 5%	4402
November	1st to 10th	Night	27% 57% 7% 8% 2	2731
	11th to 20th	Night	25% 58% 8% 6% 2	2800
	21st to end	Night	29% 59% 5% 5% 2	2800
December	1st to 10th	Night	50% 36% 6% 6% 1	4836
	11th to 20th	Night	41% 33% 7% 9% 10%	5566
	21st to end	Night	53% 29% 6% 9% 3	7480

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 11% 36% 28% 10% 2	288
	11th to 20th	Day	12% 9% 36% 34% 9%	270
	21st to end	Day	14% 7% 36% 29% 12% 1	297
February	1st to 10th	Day	13% 12% 40% 26% 9% 1	270
	11th to 20th	Day	8% 19% 38% 23% 9% 3	270
	21st to end	Day	10% 17% 43% 20% 10% 1	225
March	1st to 10th	Day	13% 12% 38% 27% 9% 1	270
	11th to 20th	Day	13% 16% 33% 23% 13% 3	270
	21st to end	Day	10% 14% 34% 30% 11% 1	297
April	1st to 10th	Day	13% 14% 34% 26% 12% 1	450
	11th to 20th	Day	18% 15% 29% 27% 10% 1	640
	21st to end	Day	19% 7% 34% 28% 11% 1	650
May	1st to 10th	Day	18% 11% 35% 26% 8% 2	653
	11th to 20th	Day	17% 11% 31% 27% 11% 3	675
	21st to end	Day	20% 8% 26% 31% 13% 2	734
June	1st to 10th	Day	14% 11% 29% 28% 16% 3	680
	11th to 20th	Day	14% 11% 34% 27% 12% 1	680
	21st to end	Day	15% 8% 28% 28% 15% 5%	680
July	1st to 10th	Day	10% 5% 26% 33% 19% 7%	671
	11th to 20th	Day	10% 9% 25% 32% 19% 4	668
	21st to end	Day	8% 6% 26% 35% 19% 7%	739
August	1st to 10th	Day	8% 6% 26% 33% 20% 6%	676
	11th to 20th	Day	11% 6% 23% 33% 19% 8%	665
	21st to end	Day	14% 7% 30% 26% 20% 3	748
September	1st to 10th	Day	12% 9% 35% 27% 17% 1	513
	11th to 20th	Day	16% 13% 34% 26% 9% 1	371
	21st to end	Day	22% 15% 34% 23% 6% 1	300
October	1st to 10th	Day	20% 16% 29% 24% 11% 1	300
	11th to 20th	Day	17% 15% 34% 30% 3	300
	21st to end	Day	22% 21% 31% 21% 4	330
November	1st to 10th	Day	20% 16% 34% 23% 8%	300
	11th to 20th	Day	19% 20% 36% 20% 6%	300
	21st to end	Day	20% 19% 35% 23% 3 1	300
December	1st to 10th	Day	17% 13% 35% 25% 9% 1	300
	11th to 20th	Day	17% 16% 43% 22% 2	300
	21st to end	Day	17% 9% 37% 23% 11% 3	330
January	1st to 10th	Night	12% 8% 34% 31% 13% 2	981
	11th to 20th	Night	15% 6% 34% 34% 10% 1	950
	21st to end	Night	15% 8% 36% 31% 9% 1	1045
February	1st to 10th	Night	13% 6% 34% 35% 11% 1	950
	11th to 20th	Night	12% 8% 33% 30% 12% 3	929
	21st to end	Night	11% 8% 37% 30% 13% 2	785
March	1st to 10th	Night	14% 8% 35% 28% 13% 1	656
	11th to 20th	Night	11% 8% 38% 33% 9% 1	570
	21st to end	Night	20% 7% 29% 28% 12% 3	627
April	1st to 10th	Night	16% 8% 31% 32% 12% 1	570
	11th to 20th	Night	20% 6% 31% 29% 13% 1	563
	21st to end	Night	19% 6% 28% 36% 11%	570
May	1st to 10th	Night	18% 7% 31% 33% 10% 1	570
	11th to 20th	Night	20% 6% 27% 33% 12% 1	561
	21st to end	Night	19% 4 28% 36% 12%	617
June	1st to 10th	Night	16% 6% 26% 34% 17% 1	570
	11th to 20th	Night	16% 6% 30% 34% 13% 1	570
	21st to end	Night	10% 5% 25% 37% 22% 1	570
July	1st to 10th	Night	7% 3 23% 41% 24% 3	555
	11th to 20th	Night	6% 5% 27% 39% 21% 2	552
	21st to end	Night	8% 4 22% 42% 22% 2	624
August	1st to 10th	Night	8% 4 20% 42% 25% 1	567
	11th to 20th	Night	12% 5% 21% 34% 25% 3	564
	21st to end	Night	12% 6% 24% 36% 21%	627
September	1st to 10th	Night	12% 6% 29% 35% 16% 2	570
	11th to 20th	Night	15% 8% 30% 31% 16% 1	570
	21st to end	Night	17% 7% 34% 29% 12% 1	579
October	1st to 10th	Night	18% 11% 35% 29% 6% 1	760
	11th to 20th	Night	21% 10% 34% 27% 7% 1	760
	21st to end	Night	22% 13% 31% 26% 7% 1	969
November	1st to 10th	Night	19% 10% 37% 25% 9% 1	975
	11th to 20th	Night	20% 10% 34% 28% 7% 1	1000
	21st to end	Night	19% 12% 40% 22% 7% 1	1000
December	1st to 10th	Night	15% 7% 36% 31% 11% 1	1000
	11th to 20th	Night	20% 10% 38% 26% 6% 1	1000
	21st to end	Night	19% 8% 32% 30% 11% 1	1100

Page generated at 2025-01-04 02:23:59. Version ac07

Copyright © 2025 Attilla Danko.