Forks of the Credit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Forks of the Credit clear sky chart from 2005-11-06 to 2025-08-05.

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	15% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	126576
	Night	14% 10% 4 10% 5% 5% 5% 4 5% 6% 32%	121466
Transparency	Day	51% 4 12% 21% 11% 1	130170
	Night	49% 4 13% 21% 12% 1	125961
Seeing	Day	21% 18% 31% 18% 8% 3	15772
	Night	20% 17% 31% 22% 9% 1	24743

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% 14% 7% 18% 5% 5% 5% 3 4 4 23%	3597
	11th to 20th	Day	9% 19% 8% 22% 8% 8% 5% 4 4 4 8%	3997
	21st to end	Day	15% 17% 8% 17% 7% 5% 5% 3 4 5% 14%	4466
February	1st to 10th	Day	13% 17% 5% 17% 8% 6% 5% 4 5% 5% 17%	1800
	11th to 20th	Day	12% 14% 6% 16% 9% 5% 4 3 5% 6% 20%	1753
	21st to end	Day	15% 18% 6% 11% 6% 4 6% 3 5% 5% 22%	1555
March	1st to 10th	Day	17% 12% 5% 11% 7% 4 4 3 4 5% 29%	4924
	11th to 20th	Day	11% 13% 6% 10% 5% 5% 4 4 5% 8% 29%	4980
	21st to end	Day	17% 15% 4 7% 5% 4 4 3 5% 5% 31%	5465
April	1st to 10th	Day	17% 15% 4 9% 5% 3 4 4 5% 6% 28%	2338
	11th to 20th	Day	18% 11% 3 7% 5% 4 3 4 4 6% 35%	2488
	21st to end	Day	20% 10% 4 7% 5% 4 4 3 5% 6% 33%	2600
May	1st to 10th	Day	20% 9% 3 7% 4 4 4 3 5% 7% 34%	5888
	11th to 20th	Day	18% 9% 3 8% 5% 5% 4 4 5% 6% 34%	6198
	21st to end	Day	18% 7% 2 6% 5% 5% 4 3 6% 6% 38%	6949
June	1st to 10th	Day	14% 7% 2 6% 5% 5% 5% 4 6% 9% 36%	2800
	11th to 20th	Day	12% 6% 2 6% 5% 5% 5% 4 7% 9% 39%	2890
	21st to end	Day	14% 6% 2 7% 5% 5% 5% 4 7% 9% 37%	3000
July	1st to 10th	Day	11% 5% 2 7% 5% 5% 6% 5% 7% 9% 39%	6727
	11th to 20th	Day	8% 4 2 6% 5% 5% 5% 4 6% 8% 46%	6320
	21st to end	Day	8% 4 2 5% 5% 5% 5% 4 6% 8% 46%	6424
August	1st to 10th	Day	16% 7% 2 6% 5% 5% 5% 4 6% 8% 36%	4156
	11th to 20th	Day	12% 8% 4 8% 5% 6% 6% 4 7% 9% 32%	4044
	21st to end	Day	10% 6% 2 7% 5% 5% 6% 4 6% 8% 40%	4404
September	1st to 10th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 8% 38%	2280
	11th to 20th	Day	12% 8% 3 6% 4 3 3 5% 6% 8% 43%	2132
	21st to end	Day	16% 8% 3 7% 5% 5% 6% 3 6% 8% 32%	2074
October	1st to 10th	Day	18% 11% 3 8% 5% 4 4 4 5% 6% 32%	1900
	11th to 20th	Day	21% 13% 4 7% 5% 5% 4 3 5% 6% 27%	1900
	21st to end	Day	24% 16% 4 9% 5% 4 4 4 4 6% 20%	2090
November	1st to 10th	Day	13% 17% 4 8% 5% 5% 5% 5% 5% 7% 28%	1691
	11th to 20th	Day	13% 15% 6% 10% 4 5% 5% 4 6% 7% 24%	1600
	21st to end	Day	16% 19% 6% 11% 6% 5% 6% 3 5% 6% 19%	1600
December	1st to 10th	Day	16% 22% 8% 12% 6% 6% 5% 3 5% 5% 12%	2600
	11th to 20th	Day	20% 21% 6% 10% 7% 3 4 3 4 5% 18%	2986
	21st to end	Day	23% 20% 7% 17% 5% 3 4 3 3 3 11%	3960
January	1st to 10th	Night	13% 12% 6% 15% 5% 4 5% 4 5% 6% 23%	6349
	11th to 20th	Night	11% 13% 7% 18% 12% 8% 7% 4 5% 5% 11%	5887
	21st to end	Night	14% 13% 7% 15% 6% 5% 6% 4 5% 7% 18%	6490
February	1st to 10th	Night	12% 16% 5% 12% 7% 5% 5% 4 6% 6% 22%	2600
	11th to 20th	Night	11% 12% 6% 15% 9% 6% 4 4 5% 7% 23%	2533
	21st to end	Night	12% 14% 5% 11% 5% 5% 5% 4 6% 7% 26%	2070
March	1st to 10th	Night	13% 10% 4 11% 4 4 5% 4 6% 7% 30%	4915
	11th to 20th	Night	9% 8% 4 9% 5% 5% 5% 4 7% 8% 36%	4979
	21st to end	Night	19% 9% 3 7% 4 4 4 3 5% 5% 38%	5467
April	1st to 10th	Night	18% 12% 3 8% 6% 5% 4 4 5% 6% 31%	2061
	11th to 20th	Night	15% 9% 4 7% 5% 5% 4 3 4 6% 38%	1877
	21st to end	Night	14% 10% 3 9% 5% 5% 4 4 5% 7% 34%	1800
May	1st to 10th	Night	20% 8% 2 6% 4 4 4 4 4 6% 37%	4053
	11th to 20th	Night	14% 8% 3 7% 5% 4 4 4 5% 7% 40%	3679
	21st to end	Night	17% 6% 2 5% 3 3 3 3 5% 6% 46%	3926
June	1st to 10th	Night	11% 6% 1 6% 5% 5% 5% 4 5% 8% 43%	1600
	11th to 20th	Night	8% 5% 2 7% 5% 5% 5% 5% 7% 9% 42%	1502
	21st to end	Night	11% 6% 2 6% 5% 3 4 4 6% 6% 48%	1400
July	1st to 10th	Night	8% 5% 2 6% 4 4 4 4 6% 9% 48%	3243
	11th to 20th	Night	10% 4 2 6% 4 4 4 3 5% 8% 51%	3636
	21st to end	Night	8% 4 1 5% 4 4 5% 3 6% 7% 53%	4428
August	1st to 10th	Night	12% 5% 2 6% 3 4 5% 3 6% 6% 49%	2861
	11th to 20th	Night	12% 5% 2 5% 3 4 4 4 5% 8% 47%	2785
	21st to end	Night	11% 5% 2 5% 4 5% 5% 3 5% 7% 48%	3220
September	1st to 10th	Night	9% 5% 2 6% 5% 4 4 4 6% 7% 49%	1900
	11th to 20th	Night	11% 4 2 5% 3 3 3 3 6% 8% 53%	2045
	21st to end	Night	15% 9% 2 7% 4 4 4 3 5% 6% 41%	2105
October	1st to 10th	Night	16% 7% 3 7% 5% 5% 4 3 5% 7% 38%	2280
	11th to 20th	Night	18% 11% 3 8% 4 5% 5% 4 4 5% 34%	2280
	21st to end	Night	20% 11% 4 8% 5% 5% 5% 4 5% 6% 27%	2508
November	1st to 10th	Night	15% 10% 4 6% 6% 4 5% 4 6% 6% 34%	2603
	11th to 20th	Night	15% 13% 4 9% 5% 6% 5% 4 6% 7% 26%	2800
	21st to end	Night	17% 13% 5% 10% 6% 4 4 4 6% 7% 24%	2800
December	1st to 10th	Night	14% 18% 8% 13% 6% 5% 6% 4 6% 6% 14%	4580
	11th to 20th	Night	13% 21% 7% 13% 7% 4 5% 4 4 5% 16%	5208
	21st to end	Night	23% 20% 7% 16% 5% 4 3 3 3 4 12%	6996

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	62% 2 12% 14% 10%	3598
	11th to 20th	Day	75% 2 10% 8% 4	4031
	21st to end	Day	71% 3 11% 9% 6%	4466
February	1st to 10th	Day	68% 2 10% 15% 4 1	1800
	11th to 20th	Day	63% 2 12% 15% 7% 1	1762
	21st to end	Day	62% 3 12% 15% 7% 1	1555
March	1st to 10th	Day	57% 2 14% 15% 11% 1	4927
	11th to 20th	Day	52% 3 15% 21% 7% 3	4980
	21st to end	Day	55% 2 9% 21% 12% 2	5465
April	1st to 10th	Day	56% 3 10% 19% 11% 1	2338
	11th to 20th	Day	50% 3 10% 22% 14% 1	2488
	21st to end	Day	52% 3 12% 19% 12% 2	2600
May	1st to 10th	Day	49% 3 12% 20% 10% 6%	5897
	11th to 20th	Day	51% 4 11% 17% 15% 1	6202
	21st to end	Day	45% 3 12% 21% 15% 3	6949
June	1st to 10th	Day	43% 5% 12% 24% 15% 1	2800
	11th to 20th	Day	39% 5% 15% 25% 15% 1	2890
	21st to end	Day	42% 5% 13% 26% 14% 1	3000
July	1st to 10th	Day	39% 6% 15% 24% 15% 1	6656
	11th to 20th	Day	32% 5% 12% 33% 16% 1	6245
	21st to end	Day	33% 6% 13% 31% 16% 1	6240
August	1st to 10th	Day	44% 5% 14% 23% 12% 1	4143
	11th to 20th	Day	45% 5% 16% 25% 9%	4083
	21st to end	Day	39% 5% 14% 32% 10% 1	4404
September	1st to 10th	Day	42% 5% 13% 28% 11% 2	2280
	11th to 20th	Day	38% 4 13% 30% 14% 1	2132
	21st to end	Day	49% 5% 13% 24% 9%	2074
October	1st to 10th	Day	43% 5% 13% 25% 13% 1	3160
	11th to 20th	Day	44% 4 14% 23% 15%	3140
	21st to end	Day	57% 5% 12% 19% 7%	3428
November	1st to 10th	Day	52% 4 14% 21% 9% 1	1691
	11th to 20th	Day	56% 5% 14% 16% 8%	1600
	21st to end	Day	65% 4 13% 16% 3	1600
December	1st to 10th	Day	70% 4 13% 9% 3	2600
	11th to 20th	Day	68% 4 12% 10% 7%	2986
	21st to end	Day	78% 3 6% 7% 6%	3960
January	1st to 10th	Night	57% 2 13% 20% 7%	6349
	11th to 20th	Night	71% 3 10% 11% 4	5928
	21st to end	Night	62% 2 14% 12% 9% 1	6490
February	1st to 10th	Night	58% 5% 11% 20% 5% 1	2600
	11th to 20th	Night	59% 4 11% 18% 8%	2535
	21st to end	Night	56% 4 13% 19% 9%	2070
March	1st to 10th	Night	50% 4 14% 18% 12% 2	4925
	11th to 20th	Night	43% 3 18% 24% 10% 2	4980
	21st to end	Night	48% 2 9% 22% 17% 2	5467
April	1st to 10th	Night	54% 3 9% 19% 13% 1	2061
	11th to 20th	Night	47% 4 9% 22% 16% 2	1877
	21st to end	Night	48% 3 11% 19% 16% 2	1800
May	1st to 10th	Night	48% 3 12% 16% 13% 7%	4060
	11th to 20th	Night	44% 5% 13% 23% 14% 2	3680
	21st to end	Night	39% 3 15% 25% 16% 2	3927
June	1st to 10th	Night	37% 5% 12% 27% 18% 2	1600
	11th to 20th	Night	35% 4 14% 26% 19% 1	1502
	21st to end	Night	36% 4 14% 27% 17% 1	1400
July	1st to 10th	Night	31% 6% 16% 25% 19% 3	3207
	11th to 20th	Night	30% 5% 12% 32% 20% 1	3588
	21st to end	Night	29% 7% 12% 32% 19% 2	4297
August	1st to 10th	Night	35% 4 13% 30% 16% 2	2850
	11th to 20th	Night	34% 5% 15% 31% 14% 1	2812
	21st to end	Night	34% 5% 12% 32% 15% 1	3220
September	1st to 10th	Night	33% 6% 15% 30% 15% 1	1900
	11th to 20th	Night	30% 4 12% 34% 19% 1	2045
	21st to end	Night	44% 4 14% 28% 11% 1	2105
October	1st to 10th	Night	34% 3 10% 28% 24% 1	3800
	11th to 20th	Night	45% 3 12% 25% 15% 1	3779
	21st to end	Night	43% 5% 17% 25% 10%	4120
November	1st to 10th	Night	46% 5% 13% 24% 11% 1	2603
	11th to 20th	Night	54% 4 14% 18% 9% 1	2800
	21st to end	Night	56% 5% 18% 18% 3 1	2800
December	1st to 10th	Night	65% 6% 14% 12% 3	4580
	11th to 20th	Night	66% 3 13% 11% 7%	5208
	21st to end	Night	74% 3 10% 8% 5%	6996

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	23% 30% 32% 14% 3 1	200
	11th to 20th	Day	26% 30% 29% 12% 3 1	293
	21st to end	Day	28% 28% 32% 10% 2	330
February	1st to 10th	Day	29% 33% 27% 10% 1	300
	11th to 20th	Day	30% 33% 31% 6%	300
	21st to end	Day	40% 26% 31% 4	249
March	1st to 10th	Day	26% 23% 32% 16% 3	492
	11th to 20th	Day	24% 23% 37% 12% 4	500
	21st to end	Day	32% 19% 32% 12% 4 1	550
April	1st to 10th	Day	27% 24% 31% 11% 5%	500
	11th to 20th	Day	31% 21% 27% 14% 6% 2	492
	21st to end	Day	26% 18% 36% 14% 5% 1	500
May	1st to 10th	Day	24% 17% 32% 17% 7% 2	503
	11th to 20th	Day	18% 17% 33% 20% 9% 3	527
	21st to end	Day	16% 14% 33% 23% 10% 4	573
June	1st to 10th	Day	16% 17% 36% 23% 7% 1	530
	11th to 20th	Day	16% 14% 34% 24% 11% 2	620
	21st to end	Day	18% 13% 35% 24% 7% 3	730
July	1st to 10th	Day	10% 8% 36% 28% 15% 4	683
	11th to 20th	Day	13% 10% 31% 26% 15% 6%	524
	21st to end	Day	10% 9% 37% 27% 12% 5%	576
August	1st to 10th	Day	12% 9% 30% 27% 17% 6%	502
	11th to 20th	Day	11% 7% 29% 26% 19% 7%	479
	21st to end	Day	14% 9% 31% 26% 16% 5%	539
September	1st to 10th	Day	14% 11% 30% 23% 13% 8%	490
	11th to 20th	Day	11% 7% 27% 24% 20% 11%	490
	21st to end	Day	19% 15% 27% 20% 14% 5%	490
October	1st to 10th	Day	24% 18% 26% 18% 10% 3	490
	11th to 20th	Day	26% 21% 32% 13% 7% 1	490
	21st to end	Day	32% 21% 27% 16% 4	539
November	1st to 10th	Day	29% 21% 31% 15% 3 1	271
	11th to 20th	Day	29% 26% 30% 10% 5% 1	200
	21st to end	Day	27% 27% 37% 10% 1	200
December	1st to 10th	Day	34% 31% 27% 9%	200
	11th to 20th	Day	35% 30% 26% 9% 1	200
	21st to end	Day	31% 27% 28% 10% 2	220
January	1st to 10th	Night	23% 27% 34% 12% 3	800
	11th to 20th	Night	27% 24% 30% 16% 3	800
	21st to end	Night	17% 21% 37% 19% 5%	880
February	1st to 10th	Night	23% 29% 31% 16% 1	800
	11th to 20th	Night	23% 24% 36% 14% 3	783
	21st to end	Night	21% 27% 35% 15% 2	660
March	1st to 10th	Night	22% 21% 35% 19% 3	800
	11th to 20th	Night	22% 22% 36% 16% 5%	800
	21st to end	Night	22% 18% 35% 20% 6%	880
April	1st to 10th	Night	26% 17% 34% 20% 2	800
	11th to 20th	Night	22% 17% 34% 19% 7% 1	693
	21st to end	Night	20% 14% 33% 25% 7%	600
May	1st to 10th	Night	18% 13% 30% 28% 10% 2	600
	11th to 20th	Night	16% 11% 32% 29% 11% 1	446
	21st to end	Night	13% 11% 30% 31% 14%	433
June	1st to 10th	Night	13% 8% 36% 31% 12% 1	400
	11th to 20th	Night	11% 10% 31% 35% 14%	400
	21st to end	Night	13% 7% 34% 34% 12% 1	400
July	1st to 10th	Night	6% 7% 29% 38% 18% 1	390
	11th to 20th	Night	9% 7% 31% 35% 17% 1	398
	21st to end	Night	9% 3 31% 37% 18% 2	657
August	1st to 10th	Night	9% 3 26% 35% 24% 1	579
	11th to 20th	Night	7% 5% 23% 39% 23% 2	564
	21st to end	Night	14% 5% 30% 26% 23% 2	684
September	1st to 10th	Night	11% 9% 28% 29% 18% 4	760
	11th to 20th	Night	13% 6% 25% 27% 22% 6%	760
	21st to end	Night	21% 11% 21% 28% 16% 4	760
October	1st to 10th	Night	20% 11% 32% 21% 14% 3	760
	11th to 20th	Night	24% 17% 30% 21% 7% 1	760
	21st to end	Night	25% 21% 29% 20% 4	836
November	1st to 10th	Night	23% 17% 30% 21% 8% 1	780
	11th to 20th	Night	22% 24% 29% 18% 6% 1	800
	21st to end	Night	25% 22% 31% 18% 4	800
December	1st to 10th	Night	28% 24% 32% 13% 3	800
	11th to 20th	Night	24% 26% 35% 12% 3	800
	21st to end	Night	31% 23% 27% 17% 2	880

Page generated at 2025-08-02 01:32:28. Version ac07

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