Old Forge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Old Forge 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% 13% 5% 10% 6% 5% 4 3 5% 6% 26%	137994
	Night	17% 15% 6% 13% 6% 5% 4 3 4 5% 24%	134061
Transparency	Day	58% 6% 10% 17% 8% 1	141461
	Night	62% 5% 9% 15% 8% 1	138683
Seeing	Day	28% 19% 29% 16% 6% 2	16656
	Night	26% 19% 28% 20% 7% 1	25793

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	10% 18% 8% 25% 11% 5% 3 2 2 2 11%	4661
	11th to 20th	Day	8% 19% 11% 25% 12% 7% 3 2 2 2 10%	4650
	21st to end	Day	9% 16% 9% 16% 10% 10% 7% 3 4 4 14%	5403
February	1st to 10th	Day	13% 19% 6% 18% 9% 6% 5% 3 3 3 14%	1890
	11th to 20th	Day	12% 17% 10% 16% 9% 4 4 3 2 4 18%	1928
	21st to end	Day	14% 19% 9% 15% 8% 5% 4 3 3 4 16%	1730
March	1st to 10th	Day	17% 17% 9% 16% 5% 3 3 2 3 3 21%	4576
	11th to 20th	Day	11% 19% 9% 9% 5% 4 3 3 4 5% 27%	4991
	21st to end	Day	19% 15% 6% 11% 5% 3 3 2 3 4 28%	5975
April	1st to 10th	Day	21% 18% 5% 8% 3 3 3 3 4 4 28%	2520
	11th to 20th	Day	18% 15% 4 8% 5% 4 4 3 4 5% 31%	2494
	21st to end	Day	21% 16% 3 7% 5% 4 3 3 5% 4 29%	2574
May	1st to 10th	Day	29% 12% 3 7% 5% 4 4 3 4 5% 23%	8168
	11th to 20th	Day	19% 11% 3 8% 5% 5% 5% 4 6% 6% 29%	8221
	21st to end	Day	23% 10% 3 7% 5% 5% 5% 4 5% 7% 28%	9060
June	1st to 10th	Day	24% 8% 3 6% 5% 4 5% 4 5% 7% 29%	2940
	11th to 20th	Day	22% 8% 2 6% 5% 4 4 4 7% 7% 30%	2870
	21st to end	Day	22% 8% 3 7% 5% 5% 4 4 7% 7% 29%	2800
July	1st to 10th	Day	14% 6% 2 6% 4 5% 6% 4 8% 10% 35%	6360
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 5% 8% 9% 34%	6360
	21st to end	Day	15% 5% 2 6% 4 5% 5% 4 6% 8% 39%	6926
August	1st to 10th	Day	19% 7% 2 7% 4 4 4 4 6% 8% 34%	4474
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 5% 6% 7% 31%	3987
	21st to end	Day	21% 6% 2 5% 4 4 4 4 5% 9% 36%	4312
September	1st to 10th	Day	19% 5% 2 5% 4 5% 5% 4 6% 7% 38%	2400
	11th to 20th	Day	18% 6% 3 6% 3 4 4 3 5% 6% 44%	2363
	21st to end	Day	20% 9% 2 5% 4 4 5% 4 5% 6% 34%	2197
October	1st to 10th	Day	26% 11% 3 6% 4 4 3 3 3 4 32%	2000
	11th to 20th	Day	21% 15% 4 6% 4 4 5% 4 5% 7% 27%	2000
	21st to end	Day	25% 17% 4 7% 4 3 4 3 4 4 25%	2030
November	1st to 10th	Day	17% 19% 5% 8% 5% 3 5% 3 4 5% 27%	1851
	11th to 20th	Day	15% 20% 7% 10% 4 4 3 2 5% 4 25%	1809
	21st to end	Day	18% 22% 8% 11% 6% 5% 4 2 3 3 18%	1680
December	1st to 10th	Day	15% 28% 9% 19% 7% 3 3 2 3 3 9%	2680
	11th to 20th	Day	17% 22% 8% 19% 6% 4 3 2 2 3 13%	3066
	21st to end	Day	17% 20% 8% 16% 5% 4 3 2 4 4 19%	4048
January	1st to 10th	Night	11% 20% 9% 23% 10% 6% 3 2 2 2 12%	8234
	11th to 20th	Night	9% 18% 11% 28% 14% 6% 3 2 2 2 7%	8235
	21st to end	Night	10% 13% 8% 17% 11% 10% 8% 4 4 4 10%	8776
February	1st to 10th	Night	13% 18% 8% 19% 9% 5% 4 2 4 3 14%	2730
	11th to 20th	Night	11% 15% 9% 19% 10% 6% 5% 3 3 4 16%	2576
	21st to end	Night	13% 16% 7% 16% 9% 7% 3 3 4 5% 17%	2076
March	1st to 10th	Night	16% 15% 5% 16% 7% 6% 4 3 3 3 21%	5484
	11th to 20th	Night	14% 17% 7% 11% 3 3 3 3 4 6% 30%	5183
	21st to end	Night	21% 15% 7% 13% 6% 3 3 2 3 4 24%	5198
April	1st to 10th	Night	20% 17% 5% 8% 4 4 4 3 4 4 27%	2100
	11th to 20th	Night	19% 16% 4 6% 5% 4 4 3 5% 5% 28%	2075
	21st to end	Night	21% 14% 3 7% 4 4 3 3 5% 5% 32%	2044
May	1st to 10th	Night	29% 15% 3 6% 4 4 4 3 4 5% 23%	4785
	11th to 20th	Night	19% 13% 3 7% 5% 4 4 3 5% 6% 32%	4639
	21st to end	Night	22% 10% 3 7% 4 4 4 4 5% 6% 30%	5114
June	1st to 10th	Night	23% 7% 2 5% 5% 4 5% 3 6% 7% 34%	1680
	11th to 20th	Night	22% 7% 2 5% 4 3 5% 3 5% 8% 36%	1640
	21st to end	Night	20% 7% 3 6% 5% 3 5% 4 5% 8% 34%	1600
July	1st to 10th	Night	15% 6% 3 6% 5% 5% 5% 4 6% 9% 36%	3600
	11th to 20th	Night	19% 7% 2 6% 4 4 4 3 5% 7% 41%	3600
	21st to end	Night	11% 8% 2 5% 4 3 4 3 5% 7% 47%	3926
August	1st to 10th	Night	22% 8% 3 6% 4 3 3 3 4 7% 37%	2673
	11th to 20th	Night	20% 10% 3 7% 4 4 3 3 5% 6% 36%	3029
	21st to end	Night	15% 8% 2 6% 4 4 4 4 5% 7% 41%	3586
September	1st to 10th	Night	17% 8% 3 7% 4 4 4 3 4 6% 42%	2000
	11th to 20th	Night	15% 8% 2 5% 4 3 3 3 3 5% 48%	2035
	21st to end	Night	21% 7% 2 5% 4 4 4 4 5% 7% 38%	2200
October	1st to 10th	Night	23% 11% 2 6% 5% 5% 4 3 4 5% 33%	2400
	11th to 20th	Night	20% 12% 3 7% 5% 4 5% 3 4 6% 31%	2400
	21st to end	Night	25% 17% 4 8% 5% 4 4 3 4 4 23%	2809
November	1st to 10th	Night	18% 17% 5% 8% 4 4 3 3 3 5% 28%	2667
	11th to 20th	Night	16% 18% 6% 11% 5% 4 4 3 4 5% 25%	2809
	21st to end	Night	18% 21% 8% 13% 5% 4 4 3 4 4 17%	2940
December	1st to 10th	Night	14% 24% 11% 22% 6% 3 3 2 3 3 9%	4720
	11th to 20th	Night	19% 22% 8% 18% 6% 3 3 2 2 2 15%	5348
	21st to end	Night	18% 21% 7% 16% 5% 4 4 3 3 4 16%	7150

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	80% 3 5% 8% 3	4662
	11th to 20th	Day	82% 2 3 4 6% 2	4680
	21st to end	Day	75% 4 7% 9% 4 1	5403
February	1st to 10th	Day	75% 4 6% 10% 4 1	1890
	11th to 20th	Day	70% 4 7% 10% 7% 1	1937
	21st to end	Day	71% 5% 8% 9% 7%	1730
March	1st to 10th	Day	69% 4 7% 9% 8% 3	4579
	11th to 20th	Day	58% 6% 15% 12% 7% 3	4991
	21st to end	Day	60% 4 6% 13% 15% 2	5975
April	1st to 10th	Day	60% 4 8% 16% 10% 2	2520
	11th to 20th	Day	56% 6% 7% 18% 12% 1	2494
	21st to end	Day	57% 6% 8% 15% 12% 3	2574
May	1st to 10th	Day	63% 6% 7% 15% 9% 1	8180
	11th to 20th	Day	53% 8% 11% 20% 7%	8225
	21st to end	Day	54% 6% 10% 23% 7%	9061
June	1st to 10th	Day	54% 7% 11% 17% 11% 1	2940
	11th to 20th	Day	51% 8% 12% 21% 8% 1	2870
	21st to end	Day	52% 8% 13% 18% 8% 1	2800
July	1st to 10th	Day	42% 7% 17% 24% 11%	6290
	11th to 20th	Day	43% 8% 13% 26% 10%	6285
	21st to end	Day	42% 6% 11% 33% 7%	6728
August	1st to 10th	Day	47% 7% 15% 20% 11%	4460
	11th to 20th	Day	49% 8% 15% 22% 6%	4026
	21st to end	Day	45% 6% 15% 28% 7%	4312
September	1st to 10th	Day	43% 8% 11% 26% 11% 1	2400
	11th to 20th	Day	41% 6% 10% 27% 15% 1	2363
	21st to end	Day	49% 6% 11% 21% 12% 1	2197
October	1st to 10th	Day	52% 4 10% 25% 9%	3260
	11th to 20th	Day	50% 5% 14% 17% 13% 1	3240
	21st to end	Day	50% 6% 14% 23% 6% 1	3255
November	1st to 10th	Day	60% 7% 10% 14% 9%	1851
	11th to 20th	Day	62% 6% 8% 12% 9% 3	1809
	21st to end	Day	71% 5% 11% 8% 4	1680
December	1st to 10th	Day	82% 4 6% 6% 2	2680
	11th to 20th	Day	78% 3 5% 10% 4	3066
	21st to end	Day	71% 3 5% 8% 12% 1	4048
January	1st to 10th	Night	80% 4 5% 7% 4	8234
	11th to 20th	Night	86% 3 3 3 3 1	8280
	21st to end	Night	77% 4 6% 7% 5% 1	8776
February	1st to 10th	Night	76% 4 6% 9% 5%	2730
	11th to 20th	Night	71% 5% 7% 10% 6%	2578
	21st to end	Night	68% 6% 9% 11% 6% 1	2076
March	1st to 10th	Night	67% 5% 7% 11% 8% 2	5494
	11th to 20th	Night	56% 5% 15% 15% 6% 3	5184
	21st to end	Night	65% 4 5% 15% 9% 1	5198
April	1st to 10th	Night	61% 5% 9% 16% 8% 1	2100
	11th to 20th	Night	57% 6% 9% 17% 11%	2075
	21st to end	Night	52% 6% 9% 18% 13% 2	2044
May	1st to 10th	Night	64% 5% 8% 12% 10% 1	4791
	11th to 20th	Night	52% 7% 11% 21% 9%	4640
	21st to end	Night	54% 7% 9% 21% 9% 1	5115
June	1st to 10th	Night	48% 8% 13% 21% 10% 1	1680
	11th to 20th	Night	46% 7% 14% 20% 11% 1	1640
	21st to end	Night	48% 8% 12% 22% 10%	1600
July	1st to 10th	Night	44% 7% 17% 20% 12% 1	3560
	11th to 20th	Night	44% 6% 13% 24% 13%	3552
	21st to end	Night	36% 5% 13% 35% 10%	3809
August	1st to 10th	Night	47% 7% 13% 24% 8%	2663
	11th to 20th	Night	49% 5% 15% 24% 7%	3056
	21st to end	Night	42% 6% 14% 30% 7% 1	3586
September	1st to 10th	Night	43% 8% 11% 26% 11% 1	2000
	11th to 20th	Night	38% 5% 12% 30% 14% 1	2035
	21st to end	Night	45% 8% 10% 23% 13% 2	2200
October	1st to 10th	Night	53% 6% 9% 21% 10% 1	3920
	11th to 20th	Night	49% 5% 12% 19% 10% 5%	3899
	21st to end	Night	55% 6% 11% 22% 6% 1	4534
November	1st to 10th	Night	59% 6% 9% 15% 9% 2	2667
	11th to 20th	Night	61% 7% 8% 13% 8% 3	2809
	21st to end	Night	71% 5% 9% 10% 4 1	2940
December	1st to 10th	Night	82% 5% 6% 5% 2	4720
	11th to 20th	Night	77% 4 5% 9% 5%	5348
	21st to end	Night	73% 4 5% 6% 10% 2	7150

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	29% 24% 34% 11% 2 1	220
	11th to 20th	Day	33% 32% 29% 5% 1	220
	21st to end	Day	27% 30% 33% 9% 1	294
February	1st to 10th	Day	36% 34% 26% 4 1	330
	11th to 20th	Day	35% 31% 28% 6%	415
	21st to end	Day	36% 27% 30% 6% 1	446
March	1st to 10th	Day	33% 24% 30% 10% 2	540
	11th to 20th	Day	34% 27% 26% 11% 2	540
	21st to end	Day	36% 27% 23% 11% 2 1	594
April	1st to 10th	Day	39% 24% 22% 11% 3 1	540
	11th to 20th	Day	35% 24% 22% 14% 4 1	532
	21st to end	Day	34% 20% 29% 11% 5% 1	540
May	1st to 10th	Day	37% 19% 26% 11% 5% 2	543
	11th to 20th	Day	25% 17% 31% 21% 5% 1	567
	21st to end	Day	23% 18% 31% 18% 9% 1	617
June	1st to 10th	Day	25% 18% 31% 20% 5% 1	570
	11th to 20th	Day	23% 15% 31% 21% 9% 2	550
	21st to end	Day	24% 16% 33% 19% 6% 2	530
July	1st to 10th	Day	19% 10% 32% 25% 10% 3	525
	11th to 20th	Day	17% 10% 33% 27% 11% 2	524
	21st to end	Day	18% 12% 37% 24% 7% 2	576
August	1st to 10th	Day	19% 10% 26% 27% 13% 5%	526
	11th to 20th	Day	20% 9% 28% 24% 13% 6%	519
	21st to end	Day	21% 13% 30% 20% 12% 5%	583
September	1st to 10th	Day	22% 12% 25% 22% 13% 6%	530
	11th to 20th	Day	17% 10% 25% 18% 20% 9%	530
	21st to end	Day	22% 13% 30% 19% 12% 4	530
October	1st to 10th	Day	28% 13% 26% 18% 10% 4	530
	11th to 20th	Day	28% 23% 28% 16% 5% 1	530
	21st to end	Day	36% 20% 25% 17% 2	489
November	1st to 10th	Day	35% 19% 29% 12% 6%	425
	11th to 20th	Day	32% 26% 26% 11% 5% 1	349
	21st to end	Day	41% 25% 27% 7%	220
December	1st to 10th	Day	35% 25% 29% 10% 1	220
	11th to 20th	Day	36% 31% 26% 5% 2	220
	21st to end	Day	34% 26% 31% 7% 1	242
January	1st to 10th	Night	28% 29% 32% 10% 1	840
	11th to 20th	Night	31% 27% 28% 13% 2	840
	21st to end	Night	21% 28% 32% 16% 3	924
February	1st to 10th	Night	25% 29% 34% 11% 1	840
	11th to 20th	Night	26% 28% 32% 12% 2	823
	21st to end	Night	27% 26% 35% 11% 2	692
March	1st to 10th	Night	27% 25% 33% 14% 1	840
	11th to 20th	Night	30% 25% 28% 14% 2	840
	21st to end	Night	29% 23% 30% 13% 5% 1	924
April	1st to 10th	Night	28% 22% 32% 16% 2	840
	11th to 20th	Night	29% 22% 27% 16% 6%	831
	21st to end	Night	32% 15% 27% 21% 5% 1	784
May	1st to 10th	Night	32% 13% 25% 23% 6%	467
	11th to 20th	Night	21% 13% 32% 26% 7%	414
	21st to end	Night	19% 8% 35% 28% 9% 2	455
June	1st to 10th	Night	25% 8% 26% 30% 10% 1	420
	11th to 20th	Night	23% 9% 23% 33% 11%	410
	21st to end	Night	24% 6% 31% 30% 9% 1	400
July	1st to 10th	Night	13% 8% 24% 39% 14% 1	390
	11th to 20th	Night	14% 4 25% 38% 16% 2	388
	21st to end	Night	16% 6% 24% 41% 12% 1	438
August	1st to 10th	Night	18% 6% 21% 37% 17% 1	446
	11th to 20th	Night	23% 4 22% 28% 22% 2	683
	21st to end	Night	19% 9% 25% 32% 14% 1	880
September	1st to 10th	Night	19% 10% 26% 30% 14% 2	800
	11th to 20th	Night	19% 7% 22% 29% 19% 3	800
	21st to end	Night	24% 10% 24% 26% 15% 1	800
October	1st to 10th	Night	28% 14% 25% 18% 13% 2	800
	11th to 20th	Night	27% 15% 30% 22% 6% 1	800
	21st to end	Night	35% 19% 27% 17% 3	880
November	1st to 10th	Night	29% 19% 30% 16% 6%	820
	11th to 20th	Night	27% 22% 31% 13% 6% 1	840
	21st to end	Night	32% 26% 26% 13% 3	840
December	1st to 10th	Night	33% 25% 28% 11% 2	840
	11th to 20th	Night	30% 29% 27% 12% 2 1	840
	21st to end	Night	33% 29% 25% 11% 2	924

Page generated at 2026-06-13 02:31:41. Version ac07

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