Caribou
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caribou clear sky chart from 2005-11-06 to 2026-06-16.

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	18% 9% 3 8% 5% 5% 5% 4 6% 7% 30%	137427
	Night	17% 11% 4 8% 5% 5% 5% 4 5% 6% 30%	134736
Transparency	Day	54% 3 13% 21% 9% 1	140898
	Night	55% 3 11% 20% 10% 1	139355
Seeing	Day	22% 13% 29% 23% 10% 2	18077
	Night	22% 10% 31% 28% 8% 1	26119

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	12% 16% 7% 12% 7% 6% 5% 4 5% 5% 21%	4110
	11th to 20th	Day	13% 14% 6% 14% 6% 5% 5% 5% 6% 7% 20%	4650
	21st to end	Day	5% 8% 5% 10% 6% 7% 8% 6% 8% 8% 28%	5124
February	1st to 10th	Day	11% 13% 5% 8% 7% 6% 6% 5% 7% 7% 26%	1871
	11th to 20th	Day	14% 12% 5% 10% 6% 5% 6% 4 6% 6% 25%	1859
	21st to end	Day	11% 9% 3 8% 8% 6% 7% 4 5% 7% 30%	1730
March	1st to 10th	Day	19% 14% 4 9% 6% 5% 5% 4 5% 6% 24%	4658
	11th to 20th	Day	16% 14% 5% 10% 6% 5% 5% 4 5% 6% 23%	5090
	21st to end	Day	21% 14% 4 8% 5% 4 5% 3 5% 6% 24%	5587
April	1st to 10th	Day	19% 11% 3 8% 6% 6% 5% 4 5% 6% 27%	2516
	11th to 20th	Day	19% 9% 3 7% 4 4 5% 4 6% 6% 33%	2702
	21st to end	Day	23% 10% 3 6% 4 4 4 3 6% 5% 32%	2730
May	1st to 10th	Day	25% 8% 3 8% 5% 5% 5% 4 5% 7% 25%	7639
	11th to 20th	Day	23% 7% 2 7% 5% 5% 5% 4 5% 7% 30%	8072
	21st to end	Day	19% 7% 3 8% 5% 5% 6% 4 6% 7% 31%	9716
June	1st to 10th	Day	20% 8% 2 7% 5% 5% 5% 4 7% 8% 28%	3150
	11th to 20th	Day	19% 7% 2 7% 5% 4 5% 4 6% 7% 34%	3075
	21st to end	Day	22% 10% 3 7% 5% 5% 5% 4 6% 7% 26%	3000
July	1st to 10th	Day	16% 6% 3 8% 6% 6% 6% 5% 7% 10% 27%	6820
	11th to 20th	Day	17% 6% 2 7% 5% 4 5% 4 6% 8% 35%	6694
	21st to end	Day	13% 5% 2 5% 5% 4 5% 5% 7% 9% 40%	6926
August	1st to 10th	Day	17% 5% 2 6% 5% 5% 6% 5% 7% 8% 34%	4246
	11th to 20th	Day	15% 8% 3 8% 5% 6% 5% 4 7% 8% 30%	4175
	21st to end	Day	17% 6% 2 6% 4 5% 5% 4 6% 9% 36%	4675
September	1st to 10th	Day	15% 6% 3 6% 4 3 5% 2 6% 7% 42%	2375
	11th to 20th	Day	16% 5% 2 4 3 4 3 3 4 6% 48%	2200
	21st to end	Day	17% 6% 2 6% 4 3 4 4 5% 8% 40%	2200
October	1st to 10th	Day	17% 8% 2 6% 5% 5% 3 3 5% 7% 39%	2093
	11th to 20th	Day	21% 8% 3 7% 4 4 4 3 5% 6% 33%	1980
	21st to end	Day	24% 9% 3 8% 5% 4 5% 3 5% 7% 26%	1980
November	1st to 10th	Day	19% 11% 3 7% 5% 6% 5% 4 5% 7% 29%	1835
	11th to 20th	Day	19% 11% 3 10% 5% 5% 5% 4 5% 6% 27%	1680
	21st to end	Day	21% 12% 3 9% 5% 5% 5% 3 5% 7% 25%	1678
December	1st to 10th	Day	17% 13% 4 8% 5% 5% 5% 3 5% 7% 28%	2350
	11th to 20th	Day	19% 9% 3 9% 6% 5% 5% 4 6% 8% 28%	2688
	21st to end	Day	17% 14% 5% 10% 5% 5% 3 3 5% 7% 25%	3553
January	1st to 10th	Night	13% 16% 6% 12% 7% 6% 6% 4 6% 6% 18%	8796
	11th to 20th	Night	13% 15% 6% 12% 8% 6% 5% 4 6% 5% 20%	8235
	21st to end	Night	5% 11% 5% 10% 7% 6% 7% 5% 6% 7% 31%	9057
February	1st to 10th	Night	11% 13% 4 9% 6% 6% 5% 4 6% 7% 29%	2747
	11th to 20th	Night	13% 14% 6% 10% 7% 6% 5% 4 5% 6% 25%	2644
	21st to end	Night	12% 14% 3 9% 6% 5% 5% 4 5% 5% 34%	2076
March	1st to 10th	Night	21% 13% 4 10% 5% 4 5% 3 4 6% 26%	5400
	11th to 20th	Night	16% 14% 5% 9% 5% 5% 5% 4 5% 7% 25%	5089
	21st to end	Night	26% 13% 3 7% 4 3 3 2 4 6% 29%	5587
April	1st to 10th	Night	22% 11% 4 7% 4 5% 4 3 5% 4 32%	2100
	11th to 20th	Night	21% 9% 2 7% 4 4 4 4 5% 7% 33%	1868
	21st to end	Night	23% 10% 2 6% 4 5% 4 3 5% 5% 32%	1890
May	1st to 10th	Night	27% 11% 2 6% 4 4 4 3 5% 6% 27%	5259
	11th to 20th	Night	23% 7% 2 7% 5% 5% 5% 4 5% 5% 32%	4844
	21st to end	Night	18% 7% 2 6% 4 4 4 4 6% 6% 39%	4491
June	1st to 10th	Night	23% 7% 3 6% 4 4 6% 4 4 7% 33%	1470
	11th to 20th	Night	17% 6% 2 6% 5% 4 4 4 8% 8% 36%	1435
	21st to end	Night	23% 8% 4 7% 6% 4 4 3 5% 5% 31%	1400
July	1st to 10th	Night	16% 7% 2 7% 6% 5% 4 4 6% 8% 35%	3160
	11th to 20th	Night	17% 6% 2 7% 4 5% 5% 4 6% 8% 36%	3265
	21st to end	Night	11% 6% 2 7% 4 5% 5% 4 6% 8% 41%	3926
August	1st to 10th	Night	18% 7% 3 7% 5% 5% 6% 4 6% 6% 33%	2870
	11th to 20th	Night	12% 6% 3 9% 6% 5% 5% 4 7% 9% 34%	2872
	21st to end	Night	17% 5% 3 6% 4 4 3 3 4 6% 45%	3223
September	1st to 10th	Night	15% 5% 2 6% 4 4 4 3 5% 8% 45%	2022
	11th to 20th	Night	15% 6% 2 5% 4 4 4 4 6% 6% 46%	2200
	21st to end	Night	17% 5% 2 5% 4 4 4 3 5% 6% 45%	2200
October	1st to 10th	Night	19% 6% 2 5% 4 3 4 3 4 6% 43%	2306
	11th to 20th	Night	19% 9% 3 6% 4 4 5% 3 5% 6% 35%	2415
	21st to end	Night	22% 10% 2 7% 5% 4 4 4 5% 6% 32%	2860
November	1st to 10th	Night	20% 10% 3 6% 5% 4 4 4 5% 6% 32%	2681
	11th to 20th	Night	20% 11% 4 7% 4 4 4 4 5% 6% 31%	2940
	21st to end	Night	20% 11% 4 9% 6% 5% 5% 4 5% 6% 25%	2940
December	1st to 10th	Night	15% 12% 5% 11% 7% 5% 5% 4 6% 6% 25%	5060
	11th to 20th	Night	22% 11% 3 8% 5% 4 4 3 5% 7% 29%	5741
	21st to end	Night	18% 13% 4 10% 5% 4 4 4 5% 7% 24%	7667

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	66% 1 9% 18% 5%	4111
	11th to 20th	Day	65% 2 10% 17% 6%	4680
	21st to end	Day	50% 2 12% 19% 16%	5124
February	1st to 10th	Day	56% 5% 11% 18% 9% 1	1871
	11th to 20th	Day	58% 3 11% 19% 7% 1	1867
	21st to end	Day	51% 5% 10% 24% 9% 1	1730
March	1st to 10th	Day	61% 2 9% 11% 14% 3	4662
	11th to 20th	Day	61% 3 15% 13% 7% 1	5090
	21st to end	Day	62% 2 5% 21% 9% 2	5587
April	1st to 10th	Day	56% 3 9% 19% 10% 2	2516
	11th to 20th	Day	50% 3 11% 23% 12% 1	2702
	21st to end	Day	54% 3 8% 20% 12% 3	2730
May	1st to 10th	Day	60% 2 9% 20% 9%	7651
	11th to 20th	Day	56% 2 13% 21% 7% 2	8076
	21st to end	Day	53% 2 10% 20% 14% 1	9717
June	1st to 10th	Day	52% 4 14% 18% 10% 1	3150
	11th to 20th	Day	49% 3 14% 21% 11% 2	3075
	21st to end	Day	58% 5% 12% 17% 9% 1	3000
July	1st to 10th	Day	52% 3 17% 19% 8%	6745
	11th to 20th	Day	48% 3 16% 28% 5%	6613
	21st to end	Day	42% 3 17% 31% 7%	6728
August	1st to 10th	Day	47% 4 18% 23% 7%	4232
	11th to 20th	Day	51% 4 17% 22% 5%	4214
	21st to end	Day	46% 3 15% 24% 11%	4675
September	1st to 10th	Day	42% 4 14% 27% 12%	2375
	11th to 20th	Day	38% 3 14% 29% 15%	2200
	21st to end	Day	42% 5% 12% 30% 11%	2200
October	1st to 10th	Day	50% 2 13% 29% 6%	3405
	11th to 20th	Day	51% 2 12% 28% 7%	3208
	21st to end	Day	50% 2 15% 21% 11%	3180
November	1st to 10th	Day	56% 3 12% 22% 7%	1835
	11th to 20th	Day	58% 5% 11% 19% 8% 1	1680
	21st to end	Day	61% 3 16% 17% 4	1678
December	1st to 10th	Day	57% 2 18% 13% 9%	2350
	11th to 20th	Day	56% 3 10% 20% 9% 2	2688
	21st to end	Day	62% 3 11% 13% 10% 1	3553
January	1st to 10th	Night	68% 2 11% 14% 5%	8796
	11th to 20th	Night	67% 2 9% 16% 6%	8280
	21st to end	Night	53% 2 8% 20% 16% 1	9057
February	1st to 10th	Night	56% 4 11% 18% 11% 1	2747
	11th to 20th	Night	61% 4 9% 17% 8% 1	2647
	21st to end	Night	54% 3 8% 21% 13% 1	2076
March	1st to 10th	Night	62% 3 7% 16% 11% 2	5409
	11th to 20th	Night	60% 2 14% 15% 8%	5090
	21st to end	Night	60% 1 4 20% 13% 1	5587
April	1st to 10th	Night	56% 3 8% 18% 12% 4	2100
	11th to 20th	Night	51% 3 9% 21% 14% 1	1868
	21st to end	Night	54% 3 7% 19% 16% 2	1890
May	1st to 10th	Night	59% 2 10% 17% 11% 1	5265
	11th to 20th	Night	55% 2 10% 23% 9% 1	4845
	21st to end	Night	47% 3 10% 22% 16% 1	4492
June	1st to 10th	Night	51% 4 11% 24% 10% 1	1470
	11th to 20th	Night	45% 4 15% 22% 12% 2	1435
	21st to end	Night	55% 4 12% 18% 10% 1	1400
July	1st to 10th	Night	50% 2 19% 21% 7%	3125
	11th to 20th	Night	47% 4 17% 28% 4	3223
	21st to end	Night	42% 3 20% 25% 9%	3809
August	1st to 10th	Night	52% 4 16% 23% 6%	2860
	11th to 20th	Night	47% 5% 23% 17% 8%	2899
	21st to end	Night	43% 3 15% 25% 14%	3223
September	1st to 10th	Night	39% 4 13% 31% 12% 1	2022
	11th to 20th	Night	39% 4 14% 29% 13%	2200
	21st to end	Night	41% 4 12% 27% 15% 1	2200
October	1st to 10th	Night	49% 2 11% 29% 9%	3774
	11th to 20th	Night	49% 2 12% 30% 7%	3926
	21st to end	Night	45% 3 19% 21% 12%	4610
November	1st to 10th	Night	54% 3 13% 22% 7%	2681
	11th to 20th	Night	55% 4 13% 18% 9% 1	2940
	21st to end	Night	61% 5% 14% 14% 5% 1	2940
December	1st to 10th	Night	64% 2 11% 19% 5%	5060
	11th to 20th	Night	58% 2 9% 21% 9% 1	5742
	21st to end	Night	61% 2 9% 19% 8% 1	7667

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	20% 17% 31% 23% 8%	220
	11th to 20th	Day	28% 16% 29% 15% 11%	220
	21st to end	Day	16% 14% 36% 19% 11% 4	242
February	1st to 10th	Day	20% 13% 31% 25% 8% 3	411
	11th to 20th	Day	16% 16% 39% 23% 5% 1	434
	21st to end	Day	16% 18% 34% 25% 7%	446
March	1st to 10th	Day	25% 14% 32% 23% 6%	540
	11th to 20th	Day	22% 16% 29% 24% 9% 1	540
	21st to end	Day	25% 15% 27% 23% 8% 2	594
April	1st to 10th	Day	27% 16% 30% 19% 7% 1	540
	11th to 20th	Day	24% 12% 29% 25% 9% 2	532
	21st to end	Day	30% 12% 25% 21% 9% 2	540
May	1st to 10th	Day	28% 15% 27% 22% 7% 1	543
	11th to 20th	Day	26% 14% 27% 21% 9% 3	664
	21st to end	Day	23% 15% 31% 22% 7% 1	845
June	1st to 10th	Day	24% 14% 28% 22% 10% 2	780
	11th to 20th	Day	22% 13% 27% 24% 12% 2	755
	21st to end	Day	26% 9% 32% 23% 10% 1	730
July	1st to 10th	Day	18% 7% 33% 27% 13% 2	720
	11th to 20th	Day	16% 8% 29% 31% 14% 1	670
	21st to end	Day	16% 5% 32% 31% 13% 2	576
August	1st to 10th	Day	17% 8% 27% 29% 14% 5%	526
	11th to 20th	Day	16% 8% 25% 28% 18% 4	519
	21st to end	Day	19% 12% 22% 25% 16% 5%	583
September	1st to 10th	Day	16% 11% 27% 25% 15% 5%	530
	11th to 20th	Day	18% 11% 24% 25% 15% 7%	530
	21st to end	Day	21% 12% 27% 22% 12% 7%	530
October	1st to 10th	Day	18% 12% 29% 21% 15% 4	470
	11th to 20th	Day	27% 16% 26% 17% 12% 3	420
	21st to end	Day	28% 16% 29% 18% 8% 1	462
November	1st to 10th	Day	28% 18% 28% 20% 6%	425
	11th to 20th	Day	26% 15% 31% 20% 8% 1	430
	21st to end	Day	28% 15% 29% 21% 5%	428
December	1st to 10th	Day	20% 15% 32% 20% 12% 2	220
	11th to 20th	Day	24% 18% 32% 20% 5% 1	220
	21st to end	Day	24% 16% 32% 18% 8% 2	242
January	1st to 10th	Night	21% 13% 36% 25% 5%	944
	11th to 20th	Night	25% 13% 31% 23% 7%	840
	21st to end	Night	14% 12% 39% 27% 8%	924
February	1st to 10th	Night	16% 12% 41% 23% 7% 1	840
	11th to 20th	Night	21% 15% 34% 24% 6%	823
	21st to end	Night	21% 11% 36% 27% 4 1	692
March	1st to 10th	Night	20% 11% 38% 28% 3	840
	11th to 20th	Night	23% 14% 32% 24% 7%	840
	21st to end	Night	23% 8% 36% 26% 6% 1	924
April	1st to 10th	Night	28% 13% 29% 25% 5%	798
	11th to 20th	Night	26% 12% 30% 25% 7%	624
	21st to end	Night	29% 10% 29% 25% 7%	630
May	1st to 10th	Night	27% 9% 31% 26% 6%	630
	11th to 20th	Night	25% 9% 31% 27% 7% 1	587
	21st to end	Night	21% 9% 33% 30% 6%	455
June	1st to 10th	Night	24% 6% 27% 35% 7% 1	420
	11th to 20th	Night	21% 4 25% 38% 12%	410
	21st to end	Night	23% 7% 27% 32% 12%	400
July	1st to 10th	Night	19% 5% 28% 35% 13%	390
	11th to 20th	Night	15% 6% 27% 41% 12%	388
	21st to end	Night	20% 4 22% 38% 16% 1	438
August	1st to 10th	Night	17% 4 20% 42% 16%	565
	11th to 20th	Night	14% 3 23% 43% 17%	592
	21st to end	Night	11% 5% 28% 37% 17% 2	660
September	1st to 10th	Night	17% 6% 31% 34% 13%	712
	11th to 20th	Night	18% 7% 24% 35% 15% 2	800
	21st to end	Night	20% 7% 26% 31% 15% 1	800
October	1st to 10th	Night	21% 7% 29% 30% 12% 1	800
	11th to 20th	Night	24% 8% 32% 26% 9%	800
	21st to end	Night	26% 11% 33% 23% 6%	880
November	1st to 10th	Night	26% 11% 33% 24% 6%	828
	11th to 20th	Night	22% 17% 30% 23% 6% 1	950
	21st to end	Night	26% 13% 32% 24% 5%	950
December	1st to 10th	Night	29% 8% 34% 23% 5% 1	950
	11th to 20th	Night	25% 15% 33% 23% 4	950
	21st to end	Night	27% 15% 30% 22% 5% 1	1045

Page generated at 2026-06-13 02:31:42. Version ac07

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