Buffalo Lake National Wildlife Refuge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Buffalo Lake National Wildlife Refuge clear sky chart from 2005-11-06 to 2025-11-18.

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	5% 4 2 4 3 3 3 3 5% 7% 62%	136211
	Night	4 4 1 4 3 3 4 3 5% 7% 61%	131477
Transparency	Day	23% 4 8% 22% 28% 16%	131291
	Night	22% 4 8% 21% 28% 17%	127403
Seeing	Day	7% 6% 27% 33% 21% 6%	16655
	Night	6% 7% 36% 38% 12% 1	26595

By Month

Percentage Cloud Cover SW (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	6% 8% 4 6% 3 3 3 3 3 5% 55%	4017
	11th to 20th	Day	2 4 1 3 2 2 3 2 4 6% 71%	4195
	21st to end	Day	6% 5% 2 6% 4 3 3 3 4 6% 58%	4994
February	1st to 10th	Day	5% 6% 2 4 3 2 3 3 5% 6% 63%	2000
	11th to 20th	Day	6% 6% 2 6% 3 3 3 3 3 6% 58%	1949
	21st to end	Day	3 6% 2 3 3 3 3 3 3 6% 65%	1650
March	1st to 10th	Day	6% 4 1 4 2 3 3 2 4 6% 64%	4500
	11th to 20th	Day	6% 5% 1 5% 3 3 3 3 4 7% 60%	4733
	21st to end	Day	3 4 2 5% 4 3 4 4 6% 8% 59%	5801
April	1st to 10th	Day	5% 4 1 4 2 2 3 3 4 6% 66%	2400
	11th to 20th	Day	7% 4 2 4 3 3 3 3 4 6% 61%	2371
	21st to end	Day	5% 3 1 3 3 3 3 3 6% 7% 64%	2400
May	1st to 10th	Day	10% 4 1 4 3 3 3 4 5% 6% 58%	5850
	11th to 20th	Day	7% 4 1 3 2 2 2 2 4 5% 67%	5862
	21st to end	Day	7% 4 1 4 3 3 3 3 4 6% 61%	6446
June	1st to 10th	Day	5% 4 2 4 4 4 4 4 7% 9% 54%	2600
	11th to 20th	Day	3 3 1 3 3 3 4 3 5% 7% 65%	2714
	21st to end	Day	3 2 1 3 4 4 5% 4 6% 8% 58%	2800
July	1st to 10th	Day	8% 5% 2 6% 4 5% 5% 4 6% 8% 49%	6339
	11th to 20th	Day	3 3 1 4 3 3 4 4 6% 9% 61%	6042
	21st to end	Day	2 3 1 4 3 4 4 4 6% 9% 60%	6348
August	1st to 10th	Day	2 2 1 4 3 3 4 3 6% 8% 62%	5348
	11th to 20th	Day	3 3 1 3 4 4 5% 4 8% 9% 57%	5366
	21st to end	Day	6% 4 2 5% 3 4 4 3 6% 9% 54%	5984
September	1st to 10th	Day	6% 4 2 4 4 3 4 4 5% 9% 56%	2400
	11th to 20th	Day	7% 4 2 5% 3 3 3 3 6% 8% 55%	2200
	21st to end	Day	6% 3 1 3 3 3 3 2 4 5% 67%	2200
October	1st to 10th	Day	4 3 1 2 2 2 2 2 3 4 76%	3590
	11th to 20th	Day	9% 4 2 4 3 3 3 3 4 5% 62%	3486
	21st to end	Day	4 2 1 2 1 2 2 2 4 4 76%	3291
November	1st to 10th	Day	5% 3 1 3 2 2 2 2 4 6% 71%	1853
	11th to 20th	Day	2 2 2 4 2 2 3 3 4 6% 71%	1863
	21st to end	Day	8% 5% 2 4 3 2 2 2 4 5% 63%	1800
December	1st to 10th	Day	3 3 1 3 2 2 3 3 5% 7% 67%	2940
	11th to 20th	Day	3 4 1 4 3 4 4 3 5% 5% 63%	3391
	21st to end	Day	4 5% 2 5% 4 3 3 2 3 4 66%	4488
January	1st to 10th	Night	5% 7% 3 7% 3 3 3 3 4 5% 57%	5888
	11th to 20th	Night	2 3 2 4 3 3 3 3 5% 5% 68%	5828
	21st to end	Night	3 5% 2 7% 4 3 3 3 5% 6% 58%	5984
February	1st to 10th	Night	5% 6% 2 5% 3 2 3 2 4 6% 63%	2400
	11th to 20th	Night	5% 6% 2 5% 4 3 3 3 4 6% 58%	2338
	21st to end	Night	5% 3 1 3 3 3 4 3 6% 6% 62%	1980
March	1st to 10th	Night	4 4 1 4 2 3 3 3 4 6% 65%	5374
	11th to 20th	Night	5% 4 1 4 3 3 3 2 4 6% 65%	5238
	21st to end	Night	3 4 2 4 3 3 3 3 5% 7% 63%	5128
April	1st to 10th	Night	5% 4 1 2 2 3 3 3 5% 6% 66%	2000
	11th to 20th	Night	6% 5% 1 3 3 3 4 3 5% 7% 61%	1977
	21st to end	Night	6% 4 1 3 2 3 3 3 5% 6% 63%	2000
May	1st to 10th	Night	8% 5% 1 4 3 3 3 3 4 6% 60%	4126
	11th to 20th	Night	5% 4 1 4 2 3 3 3 5% 6% 63%	4053
	21st to end	Night	7% 6% 1 4 3 2 3 3 4 6% 60%	4451
June	1st to 10th	Night	4 3 1 4 3 3 5% 5% 10% 10% 52%	1800
	11th to 20th	Night	3 2 1 3 3 4 3 3 7% 8% 63%	1677
	21st to end	Night	3 3 1 4 3 4 4 4 7% 10% 57%	1600
July	1st to 10th	Night	7% 5% 2 6% 5% 5% 5% 4 7% 7% 47%	3640
	11th to 20th	Night	3 3 2 5% 4 5% 5% 4 8% 10% 51%	3920
	21st to end	Night	3 3 1 4 3 4 5% 5% 7% 12% 53%	4507
August	1st to 10th	Night	3 3 1 4 3 4 5% 5% 8% 11% 54%	4464
	11th to 20th	Night	3 3 2 5% 4 5% 5% 5% 8% 11% 49%	4483
	21st to end	Night	6% 4 2 5% 3 4 5% 5% 8% 10% 48%	4993
September	1st to 10th	Night	5% 3 2 5% 4 3 3 4 5% 8% 58%	2000
	11th to 20th	Night	6% 5% 2 6% 3 3 4 3 7% 7% 56%	2199
	21st to end	Night	6% 3 1 3 2 2 3 3 4 7% 66%	2200
October	1st to 10th	Night	4 2 1 3 2 2 2 2 3 4 76%	3590
	11th to 20th	Night	8% 4 1 4 2 3 3 2 4 5% 65%	3651
	21st to end	Night	4 2 1 2 3 2 3 2 3 5% 73%	4475
November	1st to 10th	Night	5% 3 1 2 2 2 2 2 4 5% 72%	2665
	11th to 20th	Night	2 3 1 3 2 2 3 2 4 5% 73%	2692
	21st to end	Night	7% 4 2 3 3 3 3 3 5% 5% 64%	2600
December	1st to 10th	Night	5% 3 1 3 2 3 3 3 5% 6% 67%	4250
	11th to 20th	Night	3 3 2 3 2 3 4 3 5% 7% 67%	4816
	21st to end	Night	4 4 2 5% 3 3 3 2 5% 6% 63%	6490

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	34% 3 4 24% 27% 9%	4018
	11th to 20th	Day	17% 3 6% 22% 34% 18%	4195
	21st to end	Day	28% 3 5% 18% 32% 13%	4994
February	1st to 10th	Day	24% 3 7% 22% 27% 17%	2000
	11th to 20th	Day	29% 3 6% 21% 26% 16%	1959
	21st to end	Day	22% 2 3 17% 34% 22%	1650
March	1st to 10th	Day	22% 2 3 10% 28% 34%	4500
	11th to 20th	Day	25% 3 5% 16% 31% 21%	4733
	21st to end	Day	23% 3 6% 26% 30% 12%	5801
April	1st to 10th	Day	21% 3 6% 16% 31% 24%	2400
	11th to 20th	Day	25% 3 5% 19% 26% 22%	2374
	21st to end	Day	20% 4 10% 23% 30% 14%	2400
May	1st to 10th	Day	26% 6% 9% 21% 20% 18%	5850
	11th to 20th	Day	21% 4 6% 14% 25% 31%	5866
	21st to end	Day	24% 5% 9% 17% 20% 25%	6447
June	1st to 10th	Day	25% 7% 13% 28% 16% 11%	2600
	11th to 20th	Day	19% 4 8% 22% 25% 21%	2714
	21st to end	Day	22% 5% 10% 26% 23% 13%	2800
July	1st to 10th	Day	32% 7% 10% 21% 25% 5%	6271
	11th to 20th	Day	18% 7% 12% 35% 24% 5%	5969
	21st to end	Day	19% 6% 17% 34% 20% 4	6165
August	1st to 10th	Day	17% 6% 13% 30% 22% 11%	3892
	11th to 20th	Day	18% 5% 10% 23% 31% 13%	3882
	21st to end	Day	23% 6% 11% 28% 26% 6%	4311
September	1st to 10th	Day	25% 7% 12% 22% 23% 12%	2400
	11th to 20th	Day	26% 5% 9% 21% 30% 8%	2200
	21st to end	Day	21% 3 6% 22% 33% 15%	2200
October	1st to 10th	Day	16% 3 5% 13% 39% 26%	3590
	11th to 20th	Day	25% 4 7% 17% 27% 20%	3486
	21st to end	Day	14% 2 3 22% 37% 21%	3291
November	1st to 10th	Day	16% 3 6% 18% 37% 20%	1853
	11th to 20th	Day	16% 2 5% 23% 35% 18%	1863
	21st to end	Day	25% 2 4 16% 32% 21%	1800
December	1st to 10th	Day	18% 3 6% 31% 30% 12%	2940
	11th to 20th	Day	23% 2 4 18% 37% 16%	3389
	21st to end	Day	24% 3 5% 22% 31% 15%	4488
January	1st to 10th	Night	31% 2 4 28% 28% 7%	5888
	11th to 20th	Night	18% 4 8% 19% 34% 19%	5828
	21st to end	Night	27% 4 6% 19% 31% 13%	5984
February	1st to 10th	Night	25% 2 5% 18% 29% 20%	2400
	11th to 20th	Night	28% 3 7% 20% 25% 18%	2338
	21st to end	Night	21% 3 4 16% 29% 26%	1980
March	1st to 10th	Night	20% 3 3 12% 26% 36%	5374
	11th to 20th	Night	21% 3 5% 18% 21% 33%	5238
	21st to end	Night	20% 4 7% 22% 30% 17%	5128
April	1st to 10th	Night	19% 4 7% 20% 27% 24%	2000
	11th to 20th	Night	23% 4 7% 20% 24% 21%	1977
	21st to end	Night	22% 5% 10% 23% 25% 16%	2000
May	1st to 10th	Night	25% 6% 10% 19% 21% 19%	4125
	11th to 20th	Night	22% 6% 7% 13% 23% 29%	4054
	21st to end	Night	26% 6% 9% 15% 14% 30%	4452
June	1st to 10th	Night	23% 9% 18% 24% 17% 10%	1800
	11th to 20th	Night	17% 6% 12% 21% 25% 19%	1677
	21st to end	Night	22% 4 14% 28% 19% 12%	1600
July	1st to 10th	Night	34% 8% 12% 27% 17% 2	3600
	11th to 20th	Night	25% 7% 14% 27% 23% 4	3870
	21st to end	Night	22% 7% 14% 34% 20% 4	4377
August	1st to 10th	Night	21% 7% 14% 26% 19% 13%	3244
	11th to 20th	Night	22% 6% 11% 26% 27% 9%	3243
	21st to end	Night	23% 6% 15% 27% 22% 6%	3597
September	1st to 10th	Night	26% 7% 11% 21% 23% 12%	2000
	11th to 20th	Night	27% 5% 11% 24% 23% 10%	2199
	21st to end	Night	19% 4 7% 21% 34% 16%	2200
October	1st to 10th	Night	15% 3 6% 11% 33% 33%	3590
	11th to 20th	Night	23% 3 7% 17% 29% 21%	3651
	21st to end	Night	17% 2 4 18% 41% 19%	4475
November	1st to 10th	Night	16% 2 7% 19% 34% 23%	2665
	11th to 20th	Night	15% 3 3 22% 38% 19%	2692
	21st to end	Night	23% 2 4 17% 33% 20%	2600
December	1st to 10th	Night	19% 2 6% 30% 34% 9%	4250
	11th to 20th	Night	18% 3 3 16% 41% 19%	4817
	21st to end	Night	22% 4 5% 20% 35% 14%	6490

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	8% 9% 44% 26% 12% 2	300
	11th to 20th	Day	9% 14% 39% 26% 10% 2	300
	21st to end	Day	7% 9% 37% 34% 12% 1	330
February	1st to 10th	Day	7% 9% 41% 32% 10%	300
	11th to 20th	Day	10% 11% 44% 25% 7% 2	300
	21st to end	Day	7% 12% 48% 26% 7%	249
March	1st to 10th	Day	9% 6% 41% 34% 9%	300
	11th to 20th	Day	15% 10% 37% 25% 12% 2	300
	21st to end	Day	10% 12% 41% 26% 10% 1	473
April	1st to 10th	Day	8% 13% 47% 23% 9% 1	500
	11th to 20th	Day	11% 14% 43% 28% 4 1	492
	21st to end	Day	8% 12% 37% 32% 9% 2	500
May	1st to 10th	Day	9% 8% 36% 35% 12% 1	679
	11th to 20th	Day	9% 9% 29% 32% 18% 3	725
	21st to end	Day	6% 8% 34% 33% 17% 2	789
June	1st to 10th	Day	6% 5% 24% 39% 23% 4	730
	11th to 20th	Day	4 2 26% 43% 20% 5%	730
	21st to end	Day	6% 1 19% 41% 28% 5%	730
July	1st to 10th	Day	7% 1 9% 35% 33% 14%	721
	11th to 20th	Day	3 1 8% 38% 39% 11%	718
	21st to end	Day	2 1 7% 33% 42% 16%	768
August	1st to 10th	Day	2 1 8% 39% 39% 11%	527
	11th to 20th	Day	5% 3 8% 35% 33% 16%	517
	21st to end	Day	6% 1 9% 35% 34% 14%	583
September	1st to 10th	Day	6% 2 13% 38% 31% 11%	530
	11th to 20th	Day	2 2 12% 43% 31% 10%	330
	21st to end	Day	10% 3 16% 32% 32% 8%	330
October	1st to 10th	Day	10% 4 25% 31% 25% 5%	330
	11th to 20th	Day	6% 5% 28% 36% 20% 4	330
	21st to end	Day	12% 7% 28% 29% 18% 5%	363
November	1st to 10th	Day	9% 7% 32% 32% 16% 4	330
	11th to 20th	Day	3 11% 32% 36% 13% 5%	321
	21st to end	Day	12% 12% 34% 25% 12% 4	300
December	1st to 10th	Day	6% 9% 39% 30% 14% 2	300
	11th to 20th	Day	8% 9% 39% 35% 8% 1	300
	21st to end	Day	9% 13% 43% 26% 9% 1	330
January	1st to 10th	Night	6% 10% 41% 36% 8% 1	1000
	11th to 20th	Night	6% 9% 41% 34% 9%	967
	21st to end	Night	5% 7% 44% 35% 8%	880
February	1st to 10th	Night	8% 10% 46% 31% 5%	800
	11th to 20th	Night	8% 12% 48% 28% 4 1	784
	21st to end	Night	7% 11% 49% 29% 4	660
March	1st to 10th	Night	8% 11% 48% 30% 4	800
	11th to 20th	Night	10% 11% 41% 32% 5%	715
	21st to end	Night	5% 13% 54% 25% 3	660
April	1st to 10th	Night	8% 12% 51% 27% 3	600
	11th to 20th	Night	9% 11% 56% 23% 2	593
	21st to end	Night	8% 10% 50% 27% 5%	600
May	1st to 10th	Night	6% 10% 45% 34% 4	600
	11th to 20th	Night	7% 8% 38% 37% 10% 1	591
	21st to end	Night	8% 5% 46% 34% 7%	650
June	1st to 10th	Night	5% 4 38% 44% 10%	600
	11th to 20th	Night	3 3 46% 41% 7% 1	600
	21st to end	Night	3 2 29% 52% 14%	600
July	1st to 10th	Night	6% 1 17% 51% 24% 1	585
	11th to 20th	Night	4 1 11% 54% 30%	582
	21st to end	Night	3 1 8% 54% 32% 2	657
August	1st to 10th	Night	3 1 16% 47% 32% 1	597
	11th to 20th	Night	4 2 13% 55% 24% 2	594
	21st to end	Night	5% 1 11% 49% 33% 1	660
September	1st to 10th	Night	6% 2 12% 53% 26% 1	600
	11th to 20th	Night	9% 3 25% 48% 16%	600
	21st to end	Night	7% 3 23% 45% 20% 2	600
October	1st to 10th	Night	8% 3 33% 43% 14% 1	600
	11th to 20th	Night	8% 5% 39% 39% 9% 1	644
	21st to end	Night	7% 8% 33% 34% 17% 1	1015
November	1st to 10th	Night	6% 5% 36% 39% 13% 1	1025
	11th to 20th	Night	3 9% 36% 37% 13% 1	1036
	21st to end	Night	8% 8% 37% 34% 12% 1	1000
December	1st to 10th	Night	8% 9% 37% 38% 8% 1	1000
	11th to 20th	Night	6% 9% 44% 33% 7%	1000
	21st to end	Night	9% 11% 41% 32% 7%	1100

Page generated at 2025-11-14 23:56:01. Version ac07

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