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 2024-12-09.

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	17% 11% 4 9% 5% 5% 4 4 5% 7% 29%	102085
	Night	19% 13% 4 10% 5% 4 4 3 5% 6% 26%	97782
Transparency	Day	54% 8% 13% 17% 7%	105636
	Night	57% 8% 12% 16% 6% 1	102324
Seeing	Day	24% 15% 29% 23% 8% 1	17628
	Night	25% 15% 29% 23% 7% 1	25092

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	15% 14% 9% 25% 5% 5% 3 2 2 4 14%	2526
	11th to 20th	Day	12% 16% 5% 12% 6% 5% 4 3 5% 5% 24%	2530
	21st to end	Day	13% 12% 6% 15% 7% 4 5% 3 5% 6% 24%	3035
February	1st to 10th	Day	18% 14% 4 10% 6% 6% 5% 4 5% 5% 24%	1710
	11th to 20th	Day	16% 15% 4 10% 6% 5% 5% 4 5% 6% 26%	1663
	21st to end	Day	10% 12% 5% 8% 5% 5% 5% 4 6% 8% 31%	1483
March	1st to 10th	Day	23% 12% 3 7% 5% 6% 4 3 4 5% 29%	3292
	11th to 20th	Day	12% 17% 7% 10% 7% 6% 5% 4 5% 5% 22%	3480
	21st to end	Day	21% 19% 6% 11% 6% 4 4 3 3 4 20%	3901
April	1st to 10th	Day	18% 14% 4 8% 5% 4 3 3 5% 6% 29%	2280
	11th to 20th	Day	21% 10% 3 7% 4 5% 4 3 5% 7% 32%	2268
	21st to end	Day	20% 12% 3 7% 4 4 4 4 6% 6% 30%	2470
May	1st to 10th	Day	28% 13% 3 6% 4 4 3 3 5% 7% 25%	4379
	11th to 20th	Day	17% 8% 2 7% 5% 4 5% 4 6% 7% 34%	4398
	21st to end	Day	16% 8% 2 8% 5% 5% 5% 4 6% 9% 31%	4836
June	1st to 10th	Day	24% 9% 3 6% 5% 5% 5% 5% 6% 7% 24%	2660
	11th to 20th	Day	19% 9% 2 7% 4 4 4 3 5% 7% 35%	2660
	21st to end	Day	20% 9% 3 8% 5% 5% 4 4 6% 6% 31%	2823
July	1st to 10th	Day	17% 7% 2 6% 5% 4 5% 5% 6% 8% 33%	4440
	11th to 20th	Day	14% 6% 2 6% 5% 5% 5% 4 7% 8% 36%	4440
	21st to end	Day	12% 6% 2 7% 5% 4 5% 4 6% 9% 40%	4815
August	1st to 10th	Day	16% 9% 3 9% 5% 5% 5% 5% 7% 8% 30%	4177
	11th to 20th	Day	13% 6% 2 7% 5% 5% 5% 4 6% 8% 38%	4045
	21st to end	Day	10% 5% 2 6% 5% 4 5% 4 6% 8% 46%	4283
September	1st to 10th	Day	16% 5% 3 6% 4 4 4 4 5% 7% 41%	2280
	11th to 20th	Day	16% 8% 3 6% 5% 5% 4 4 5% 6% 38%	2280
	21st to end	Day	16% 8% 3 7% 4 3 4 3 5% 7% 38%	1988
October	1st to 10th	Day	18% 9% 2 7% 4 4 5% 3 5% 7% 34%	1900
	11th to 20th	Day	20% 11% 4 9% 5% 5% 5% 3 5% 7% 26%	1900
	21st to end	Day	20% 16% 3 8% 5% 4 5% 3 5% 6% 23%	2019
November	1st to 10th	Day	20% 17% 4 8% 5% 5% 5% 4 6% 5% 21%	1651
	11th to 20th	Day	21% 21% 6% 9% 6% 4 3 3 5% 5% 18%	1600
	21st to end	Day	19% 19% 6% 14% 6% 4 4 3 5% 5% 15%	1600
December	1st to 10th	Day	22% 18% 8% 14% 6% 5% 4 4 4 4 11%	1584
	11th to 20th	Day	24% 20% 6% 16% 7% 5% 4 3 4 3 8%	1906
	21st to end	Day	20% 16% 9% 15% 6% 5% 3 2 3 4 17%	2783
January	1st to 10th	Night	14% 14% 8% 23% 6% 4 4 3 3 4 16%	4429
	11th to 20th	Night	16% 14% 6% 17% 7% 5% 3 3 4 5% 21%	4440
	21st to end	Night	14% 14% 7% 17% 7% 5% 5% 4 5% 5% 19%	4619
February	1st to 10th	Night	19% 14% 5% 10% 6% 5% 5% 3 5% 5% 25%	2470
	11th to 20th	Night	16% 15% 4 11% 9% 6% 4 3 4 5% 22%	2403
	21st to end	Night	11% 17% 6% 9% 7% 5% 3 2 5% 5% 30%	1970
March	1st to 10th	Night	22% 14% 5% 9% 5% 5% 4 3 4 5% 24%	3546
	11th to 20th	Night	21% 18% 6% 10% 5% 5% 4 3 3 4 20%	3479
	21st to end	Night	23% 16% 7% 10% 6% 4 4 3 3 3 21%	3730
April	1st to 10th	Night	22% 14% 4 9% 5% 4 4 3 5% 6% 25%	1900
	11th to 20th	Night	20% 11% 4 7% 4 4 3 3 5% 6% 32%	1860
	21st to end	Night	24% 11% 3 7% 5% 5% 4 3 4 5% 28%	1710
May	1st to 10th	Night	33% 14% 4 7% 4 4 3 3 4 5% 21%	2570
	11th to 20th	Night	18% 9% 3 8% 6% 5% 5% 3 5% 6% 34%	2506
	21st to end	Night	17% 10% 3 8% 6% 6% 6% 5% 5% 7% 26%	2749
June	1st to 10th	Night	26% 9% 3 7% 5% 4 4 3 5% 7% 26%	1520
	11th to 20th	Night	21% 7% 2 6% 4 3 3 3 6% 7% 38%	1520
	21st to end	Night	22% 8% 3 7% 5% 5% 4 4 6% 7% 30%	1356
July	1st to 10th	Night	16% 9% 3 8% 6% 5% 5% 4 7% 8% 29%	2488
	11th to 20th	Night	15% 7% 3 6% 5% 4 5% 4 7% 10% 34%	2530
	21st to end	Night	13% 6% 2 6% 4 4 4 4 7% 8% 41%	2750
August	1st to 10th	Night	16% 9% 3 7% 6% 5% 5% 4 7% 8% 30%	2752
	11th to 20th	Night	14% 7% 2 7% 5% 5% 5% 4 5% 9% 37%	2782
	21st to end	Night	14% 5% 2 6% 4 5% 5% 4 6% 8% 42%	3372
September	1st to 10th	Night	13% 6% 3 7% 5% 4 5% 3 6% 8% 41%	1900
	11th to 20th	Night	18% 7% 2 5% 3 4 4 3 5% 6% 42%	1900
	21st to end	Night	19% 6% 3 6% 5% 4 4 4 6% 8% 37%	2190
October	1st to 10th	Night	20% 8% 3 7% 4 5% 4 3 6% 7% 36%	2280
	11th to 20th	Night	19% 11% 3 8% 4 4 4 3 6% 7% 30%	2280
	21st to end	Night	26% 13% 3 9% 5% 4 4 3 4 6% 24%	2578
November	1st to 10th	Night	19% 18% 4 8% 5% 5% 4 3 4 6% 24%	2647
	11th to 20th	Night	23% 18% 4 9% 6% 4 4 4 5% 5% 17%	2800
	21st to end	Night	24% 19% 5% 10% 5% 5% 4 4 4 5% 16%	2800
December	1st to 10th	Night	23% 19% 8% 14% 6% 4 3 3 4 4 12%	2779
	11th to 20th	Night	25% 18% 5% 16% 8% 4 3 2 3 3 12%	3293
	21st to end	Night	28% 17% 6% 14% 4 3 3 2 3 4 17%	4884

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	72% 7% 13% 6% 2	2527
	11th to 20th	Day	61% 8% 10% 13% 8%	2530
	21st to end	Day	63% 6% 10% 13% 8% 1	3035
February	1st to 10th	Day	63% 5% 11% 13% 7% 1	1710
	11th to 20th	Day	62% 7% 10% 15% 6%	1671
	21st to end	Day	54% 7% 13% 16% 8% 2	1483
March	1st to 10th	Day	60% 4 11% 16% 8%	3296
	11th to 20th	Day	64% 8% 10% 12% 5% 1	3480
	21st to end	Day	71% 5% 9% 10% 5% 1	3901
April	1st to 10th	Day	60% 6% 9% 14% 10% 2	2280
	11th to 20th	Day	55% 7% 9% 18% 10% 1	2268
	21st to end	Day	56% 8% 11% 14% 9% 2	2470
May	1st to 10th	Day	61% 9% 12% 12% 5% 1	4394
	11th to 20th	Day	49% 10% 14% 19% 7%	4402
	21st to end	Day	48% 12% 16% 17% 7%	4836
June	1st to 10th	Day	59% 9% 12% 16% 4	2660
	11th to 20th	Day	49% 7% 13% 20% 9% 1	2660
	21st to end	Day	56% 9% 11% 14% 9% 1	2823
July	1st to 10th	Day	48% 9% 15% 17% 11%	4370
	11th to 20th	Day	43% 9% 18% 22% 7%	4364
	21st to end	Day	42% 10% 19% 22% 6%	4662
August	1st to 10th	Day	52% 10% 13% 20% 5%	4163
	11th to 20th	Day	45% 9% 14% 24% 8%	4084
	21st to end	Day	35% 8% 15% 29% 13%	4283
September	1st to 10th	Day	43% 8% 15% 23% 11%	2280
	11th to 20th	Day	46% 7% 13% 22% 12%	2280
	21st to end	Day	45% 8% 12% 24% 11%	1988
October	1st to 10th	Day	50% 8% 14% 21% 8%	3160
	11th to 20th	Day	50% 8% 12% 22% 9%	3140
	21st to end	Day	51% 6% 16% 19% 8%	3313
November	1st to 10th	Day	62% 7% 11% 15% 5%	1651
	11th to 20th	Day	66% 8% 13% 10% 3	1600
	21st to end	Day	66% 9% 14% 9% 2	1600
December	1st to 10th	Day	69% 8% 12% 9% 2	1584
	11th to 20th	Day	75% 7% 9% 7% 2 1	1905
	21st to end	Day	69% 7% 15% 7% 2	2783
January	1st to 10th	Night	68% 8% 12% 10% 2	4429
	11th to 20th	Night	61% 7% 11% 15% 6%	4440
	21st to end	Night	65% 8% 10% 13% 5%	4619
February	1st to 10th	Night	62% 6% 10% 13% 8% 1	2470
	11th to 20th	Night	64% 6% 10% 13% 6% 1	2406
	21st to end	Night	57% 5% 11% 18% 8% 1	1970
March	1st to 10th	Night	64% 5% 8% 13% 9% 1	3555
	11th to 20th	Night	65% 7% 8% 13% 5% 1	3480
	21st to end	Night	68% 5% 7% 13% 6% 1	3730
April	1st to 10th	Night	61% 7% 10% 12% 8% 2	1900
	11th to 20th	Night	53% 6% 10% 19% 12% 1	1860
	21st to end	Night	58% 7% 9% 14% 11% 1	1710
May	1st to 10th	Night	65% 7% 8% 13% 5%	2575
	11th to 20th	Night	48% 11% 12% 21% 7%	2507
	21st to end	Night	53% 10% 18% 14% 5%	2750
June	1st to 10th	Night	57% 7% 12% 18% 5%	1520
	11th to 20th	Night	45% 7% 14% 20% 14%	1520
	21st to end	Night	52% 10% 13% 17% 7% 1	1356
July	1st to 10th	Night	49% 9% 16% 17% 7% 1	2449
	11th to 20th	Night	42% 10% 20% 19% 9%	2482
	21st to end	Night	40% 9% 17% 25% 9%	2663
August	1st to 10th	Night	49% 10% 15% 22% 4	2741
	11th to 20th	Night	43% 11% 15% 26% 5%	2809
	21st to end	Night	37% 9% 17% 25% 11% 1	3371
September	1st to 10th	Night	40% 8% 14% 28% 11% 1	1900
	11th to 20th	Night	42% 7% 12% 27% 12% 1	1900
	21st to end	Night	45% 7% 13% 25% 9%	2190
October	1st to 10th	Night	52% 7% 13% 19% 8%	3800
	11th to 20th	Night	42% 10% 12% 26% 10%	3779
	21st to end	Night	51% 7% 13% 20% 9% 1	4238
November	1st to 10th	Night	60% 7% 12% 15% 5%	2647
	11th to 20th	Night	64% 8% 13% 11% 4	2800
	21st to end	Night	65% 9% 14% 10% 1	2800
December	1st to 10th	Night	69% 7% 12% 10% 2	2779
	11th to 20th	Night	74% 6% 8% 8% 2	3295
	21st to end	Night	70% 5% 13% 9% 2	4884

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	30% 22% 35% 13% 1	370
	11th to 20th	Day	27% 26% 28% 15% 3 1	370
	21st to end	Day	20% 20% 40% 18% 2	407
February	1st to 10th	Day	30% 21% 32% 14% 3	370
	11th to 20th	Day	27% 26% 28% 15% 4	366
	21st to end	Day	19% 21% 34% 21% 5% 1	307
March	1st to 10th	Day	22% 20% 37% 17% 4	418
	11th to 20th	Day	20% 22% 33% 20% 4 1	460
	21st to end	Day	29% 21% 31% 13% 5% 1	506
April	1st to 10th	Day	28% 25% 33% 10% 3	460
	11th to 20th	Day	25% 25% 29% 17% 4 1	452
	21st to end	Day	27% 15% 31% 20% 6% 1	460
May	1st to 10th	Day	32% 15% 28% 18% 5% 3	620
	11th to 20th	Day	20% 11% 30% 26% 10% 2	674
	21st to end	Day	23% 11% 34% 26% 5% 1	735
June	1st to 10th	Day	33% 9% 29% 21% 7% 1	680
	11th to 20th	Day	21% 8% 30% 30% 10% 2	680
	21st to end	Day	25% 9% 24% 29% 12% 1	680
July	1st to 10th	Day	17% 5% 30% 34% 13% 1	670
	11th to 20th	Day	15% 6% 27% 34% 17% 1	668
	21st to end	Day	16% 4 26% 36% 15% 2	740
August	1st to 10th	Day	16% 5% 23% 37% 17% 3	532
	11th to 20th	Day	20% 7% 23% 29% 15% 6%	479
	21st to end	Day	14% 8% 25% 34% 15% 4	539
September	1st to 10th	Day	15% 11% 29% 32% 11% 2	490
	11th to 20th	Day	22% 12% 25% 25% 12% 3	490
	21st to end	Day	21% 12% 29% 21% 15% 2	430
October	1st to 10th	Day	21% 13% 28% 26% 11% 2	390
	11th to 20th	Day	25% 17% 26% 20% 10% 1	390
	21st to end	Day	27% 21% 28% 18% 5% 1	429
November	1st to 10th	Day	31% 19% 31% 15% 3 1	395
	11th to 20th	Day	36% 22% 26% 13% 2 1	400
	21st to end	Day	35% 23% 28% 12% 2	400
December	1st to 10th	Day	30% 24% 31% 13% 3	394
	11th to 20th	Day	38% 24% 27% 10% 1	370
	21st to end	Day	25% 29% 31% 13% 2	407
January	1st to 10th	Night	27% 24% 33% 15% 2	850
	11th to 20th	Night	26% 21% 32% 18% 2	850
	21st to end	Night	22% 21% 34% 19% 4 1	859
February	1st to 10th	Night	28% 17% 31% 22% 3	760
	11th to 20th	Night	26% 22% 31% 17% 4	743
	21st to end	Night	18% 18% 34% 22% 7%	628
March	1st to 10th	Night	23% 17% 36% 20% 4	760
	11th to 20th	Night	22% 17% 30% 23% 8%	760
	21st to end	Night	27% 16% 28% 22% 6% 1	788
April	1st to 10th	Night	29% 18% 28% 20% 5%	570
	11th to 20th	Night	25% 15% 30% 23% 7% 1	564
	21st to end	Night	27% 12% 28% 25% 7% 1	570
May	1st to 10th	Night	32% 11% 27% 21% 8% 2	570
	11th to 20th	Night	25% 7% 30% 29% 8% 1	562
	21st to end	Night	22% 9% 38% 26% 5%	616
June	1st to 10th	Night	30% 7% 28% 28% 7%	570
	11th to 20th	Night	22% 9% 28% 33% 8% 1	570
	21st to end	Night	22% 6% 28% 34% 10%	406
July	1st to 10th	Night	16% 5% 26% 40% 12%	527
	11th to 20th	Night	15% 5% 26% 39% 14% 1	552
	21st to end	Night	17% 5% 25% 38% 14% 1	623
August	1st to 10th	Night	15% 3 26% 39% 16% 1	568
	11th to 20th	Night	19% 6% 23% 34% 15% 2	562
	21st to end	Night	14% 6% 23% 39% 16% 1	627
September	1st to 10th	Night	15% 9% 29% 37% 10% 1	570
	11th to 20th	Night	21% 10% 23% 31% 14% 1	570
	21st to end	Night	22% 10% 31% 27% 8% 1	746
October	1st to 10th	Night	24% 11% 29% 25% 10% 1	760
	11th to 20th	Night	25% 15% 30% 21% 8% 1	760
	21st to end	Night	33% 19% 29% 16% 4	873
November	1st to 10th	Night	30% 21% 29% 15% 4 1	880
	11th to 20th	Night	34% 20% 26% 15% 4 1	900
	21st to end	Night	36% 20% 27% 15% 2	900
December	1st to 10th	Night	31% 22% 31% 12% 4	893
	11th to 20th	Night	33% 27% 28% 10% 1	850
	21st to end	Night	33% 24% 28% 13% 2 1	935

Page generated at 2024-12-06 04:54:48. Version ac07

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