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 2025-02-21.

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% 4 4 3 5% 6% 26%	108659
	Night	17% 15% 6% 13% 6% 4 4 3 4 5% 24%	109924
Transparency	Day	57% 6% 10% 17% 8% 1	112172
	Night	62% 6% 9% 15% 7% 1	114575
Seeing	Day	28% 19% 28% 16% 7% 2	14924
	Night	26% 19% 28% 20% 7% 1	24174

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% 17% 8% 24% 12% 4 3 2 2 2 12%	3597
	11th to 20th	Day	9% 18% 8% 26% 13% 5% 3 2 2 3 10%	3570
	21st to end	Day	11% 19% 10% 16% 8% 7% 6% 3 4 4 13%	4170
February	1st to 10th	Day	13% 20% 6% 18% 9% 6% 4 3 3 3 14%	1800
	11th to 20th	Day	12% 17% 9% 15% 9% 5% 4 3 2 4 18%	1834
	21st to end	Day	14% 19% 8% 14% 8% 5% 4 3 3 4 18%	1570
March	1st to 10th	Day	21% 18% 7% 11% 6% 3 3 3 3 4 21%	3116
	11th to 20th	Day	11% 23% 11% 10% 5% 3 3 3 4 4 23%	3411
	21st to end	Day	16% 15% 6% 10% 6% 3 3 2 4 5% 31%	4084
April	1st to 10th	Day	20% 18% 5% 7% 3 3 3 2 4 5% 29%	2280
	11th to 20th	Day	19% 15% 4 7% 5% 3 4 3 4 5% 32%	2254
	21st to end	Day	22% 16% 3 7% 4 4 3 3 5% 4 29%	2328
May	1st to 10th	Day	25% 12% 3 7% 4 4 4 3 4 6% 28%	4385
	11th to 20th	Day	18% 9% 3 8% 6% 5% 5% 4 6% 7% 28%	4398
	21st to end	Day	17% 7% 2 7% 5% 4 5% 4 5% 8% 36%	4837
June	1st to 10th	Day	25% 8% 3 6% 5% 5% 5% 5% 5% 7% 27%	2660
	11th to 20th	Day	22% 8% 2 6% 5% 4 4 4 7% 7% 30%	2660
	21st to end	Day	22% 8% 3 7% 5% 5% 4 4 7% 7% 28%	2660
July	1st to 10th	Day	16% 7% 2 6% 4 5% 5% 4 8% 10% 34%	4440
	11th to 20th	Day	15% 6% 2 6% 5% 5% 5% 5% 9% 10% 31%	4440
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 5% 7% 8% 34%	4814
August	1st to 10th	Day	20% 7% 3 7% 4 4 4 4 6% 8% 33%	4337
	11th to 20th	Day	18% 8% 3 8% 5% 5% 5% 5% 6% 7% 30%	3863
	21st to end	Day	21% 6% 2 5% 4 4 4 4 5% 9% 36%	4180
September	1st to 10th	Day	19% 5% 2 6% 4 5% 5% 4 6% 7% 37%	2280
	11th to 20th	Day	18% 7% 3 6% 3 4 4 3 5% 6% 42%	2245
	21st to end	Day	20% 9% 2 5% 4 4 5% 4 5% 6% 34%	2087
October	1st to 10th	Day	27% 11% 3 7% 5% 5% 3 3 3 4 30%	1900
	11th to 20th	Day	21% 15% 4 6% 4 3 4 4 5% 7% 27%	1900
	21st to end	Day	26% 17% 4 7% 4 3 4 3 4 4 24%	1929
November	1st to 10th	Day	17% 18% 5% 8% 5% 3 5% 3 4 5% 27%	1761
	11th to 20th	Day	16% 19% 6% 9% 4 4 4 3 5% 4 26%	1723
	21st to end	Day	18% 21% 8% 11% 6% 5% 4 3 3 3 18%	1600
December	1st to 10th	Day	16% 28% 9% 19% 7% 3 3 2 3 3 9%	2600
	11th to 20th	Day	18% 22% 9% 19% 5% 4 3 2 2 3 13%	2986
	21st to end	Day	17% 20% 8% 15% 5% 4 3 2 4 4 19%	3960
January	1st to 10th	Night	11% 18% 9% 25% 11% 6% 3 2 2 2 12%	6349
	11th to 20th	Night	8% 17% 10% 29% 13% 5% 3 2 2 2 8%	6315
	21st to end	Night	12% 15% 8% 19% 10% 8% 7% 3 4 4 11%	6784
February	1st to 10th	Night	14% 19% 8% 19% 9% 5% 3 2 4 3 14%	2600
	11th to 20th	Night	11% 15% 9% 18% 10% 6% 5% 3 4 4 16%	2450
	21st to end	Night	14% 16% 7% 15% 8% 7% 4 3 4 5% 18%	1885
March	1st to 10th	Night	19% 15% 5% 12% 7% 4 4 3 3 4 24%	3724
	11th to 20th	Night	15% 21% 9% 11% 4 3 3 2 3 4 25%	3543
	21st to end	Night	18% 15% 5% 11% 6% 3 3 2 3 4 30%	3547
April	1st to 10th	Night	20% 17% 5% 8% 4 4 4 3 4 4 27%	1900
	11th to 20th	Night	19% 15% 4 6% 5% 3 4 3 6% 5% 29%	1875
	21st to end	Night	22% 14% 3 7% 4 3 3 3 5% 5% 32%	1850
May	1st to 10th	Night	25% 12% 3 6% 4 5% 4 3 5% 5% 28%	2583
	11th to 20th	Night	18% 13% 3 7% 5% 4 4 3 5% 5% 33%	2495
	21st to end	Night	18% 8% 2 6% 4 5% 5% 4 6% 7% 37%	2738
June	1st to 10th	Night	22% 7% 2 6% 5% 4 5% 4 6% 6% 33%	1520
	11th to 20th	Night	21% 7% 2 5% 4 3 5% 4 5% 8% 37%	1520
	21st to end	Night	21% 7% 3 6% 5% 3 5% 4 6% 8% 33%	1520
July	1st to 10th	Night	15% 6% 3 7% 5% 5% 6% 4 5% 7% 36%	2520
	11th to 20th	Night	17% 7% 2 6% 4 4 4 4 5% 7% 41%	2520
	21st to end	Night	14% 9% 2 6% 4 3 4 3 5% 7% 43%	2739
August	1st to 10th	Night	22% 8% 3 7% 4 3 3 3 4 6% 36%	2590
	11th to 20th	Night	21% 10% 3 7% 4 3 3 3 5% 6% 35%	2934
	21st to end	Night	15% 8% 2 6% 4 4 4 4 5% 8% 41%	3476
September	1st to 10th	Night	17% 8% 3 7% 4 4 4 3 4 6% 41%	1900
	11th to 20th	Night	16% 9% 2 5% 4 3 3 3 3 6% 47%	1933
	21st to end	Night	20% 7% 2 5% 3 4 4 4 5% 7% 38%	2090
October	1st to 10th	Night	24% 11% 2 6% 5% 5% 4 3 4 5% 31%	2280
	11th to 20th	Night	21% 13% 3 7% 5% 4 5% 3 4 5% 31%	2280
	21st to end	Night	26% 17% 4 8% 5% 4 4 3 4 4 22%	2668
November	1st to 10th	Night	18% 17% 5% 8% 4 5% 4 3 3 5% 28%	2537
	11th to 20th	Night	17% 18% 5% 9% 5% 4 4 3 4 5% 25%	2675
	21st to end	Night	18% 20% 7% 12% 5% 4 4 3 4 4 17%	2800
December	1st to 10th	Night	15% 24% 11% 23% 6% 3 3 2 3 3 8%	4580
	11th to 20th	Night	19% 22% 8% 18% 5% 3 3 2 2 2 15%	5208
	21st to end	Night	18% 21% 7% 16% 5% 4 4 3 3 4 16%	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	78% 4 5% 8% 4	3598
	11th to 20th	Day	82% 3 4 5% 5% 2	3600
	21st to end	Day	75% 5% 8% 7% 4 1	4170
February	1st to 10th	Day	76% 4 7% 10% 4 1	1800
	11th to 20th	Day	70% 5% 7% 10% 8% 1	1843
	21st to end	Day	69% 6% 8% 10% 7%	1570
March	1st to 10th	Day	67% 5% 8% 10% 8% 1	3119
	11th to 20th	Day	63% 8% 12% 10% 7% 1	3411
	21st to end	Day	56% 5% 7% 16% 14% 2	4084
April	1st to 10th	Day	59% 4 8% 16% 11% 2	2280
	11th to 20th	Day	54% 6% 7% 19% 13% 1	2254
	21st to end	Day	58% 6% 8% 14% 11% 3	2328
May	1st to 10th	Day	56% 7% 9% 19% 8% 1	4399
	11th to 20th	Day	51% 11% 12% 19% 6% 1	4402
	21st to end	Day	44% 8% 12% 25% 9% 1	4837
June	1st to 10th	Day	55% 8% 12% 15% 10% 1	2660
	11th to 20th	Day	50% 8% 12% 21% 9% 1	2660
	21st to end	Day	53% 8% 13% 18% 7% 1	2660
July	1st to 10th	Day	43% 7% 15% 25% 10%	4370
	11th to 20th	Day	43% 9% 15% 27% 6%	4365
	21st to end	Day	47% 8% 12% 25% 8%	4661
August	1st to 10th	Day	48% 7% 14% 19% 11% 1	4323
	11th to 20th	Day	50% 8% 16% 21% 5%	3902
	21st to end	Day	45% 6% 14% 28% 7%	4180
September	1st to 10th	Day	44% 8% 11% 25% 11% 1	2280
	11th to 20th	Day	42% 6% 10% 26% 14% 1	2245
	21st to end	Day	49% 6% 11% 21% 12% 1	2087
October	1st to 10th	Day	53% 4 9% 25% 8%	3160
	11th to 20th	Day	50% 5% 14% 18% 13% 1	3140
	21st to end	Day	50% 6% 14% 24% 5% 1	3154
November	1st to 10th	Day	59% 7% 11% 14% 9%	1761
	11th to 20th	Day	61% 7% 8% 12% 10% 3	1723
	21st to end	Day	71% 6% 11% 8% 4	1600
December	1st to 10th	Day	82% 4 6% 6% 1	2600
	11th to 20th	Day	78% 3 5% 10% 3	2986
	21st to end	Day	71% 3 5% 8% 12% 1	3960
January	1st to 10th	Night	80% 4 5% 7% 4	6349
	11th to 20th	Night	85% 4 4 4 3 1	6360
	21st to end	Night	78% 4 6% 7% 4 1	6784
February	1st to 10th	Night	76% 4 6% 8% 5%	2600
	11th to 20th	Night	71% 5% 7% 10% 6%	2452
	21st to end	Night	67% 6% 9% 11% 6% 1	1885
March	1st to 10th	Night	64% 6% 7% 14% 8% 1	3734
	11th to 20th	Night	63% 6% 10% 15% 6% 1	3544
	21st to end	Night	57% 5% 7% 16% 12% 2	3547
April	1st to 10th	Night	60% 5% 9% 16% 8% 2	1900
	11th to 20th	Night	56% 7% 9% 17% 11%	1875
	21st to end	Night	54% 6% 9% 17% 12% 2	1850
May	1st to 10th	Night	57% 7% 10% 15% 9% 1	2589
	11th to 20th	Night	51% 9% 12% 19% 8% 1	2496
	21st to end	Night	44% 9% 11% 21% 14% 1	2739
June	1st to 10th	Night	48% 8% 14% 20% 8% 1	1520
	11th to 20th	Night	45% 7% 15% 21% 11% 1	1520
	21st to end	Night	48% 8% 12% 21% 9%	1520
July	1st to 10th	Night	46% 7% 14% 18% 14% 1	2480
	11th to 20th	Night	42% 7% 15% 26% 10%	2472
	21st to end	Night	41% 6% 14% 30% 9% 1	2651
August	1st to 10th	Night	48% 7% 13% 23% 8%	2580
	11th to 20th	Night	50% 6% 15% 24% 6%	2961
	21st to end	Night	42% 6% 14% 30% 7% 1	3476
September	1st to 10th	Night	44% 8% 11% 25% 11% 1	1900
	11th to 20th	Night	39% 5% 12% 29% 14% 1	1933
	21st to end	Night	45% 8% 11% 24% 12% 2	2090
October	1st to 10th	Night	54% 6% 9% 21% 9% 1	3800
	11th to 20th	Night	49% 5% 12% 19% 10% 5%	3779
	21st to end	Night	55% 6% 11% 22% 5% 1	4393
November	1st to 10th	Night	59% 6% 10% 15% 9% 2	2537
	11th to 20th	Night	60% 7% 8% 13% 8% 3	2675
	21st to end	Night	70% 5% 9% 10% 4 1	2800
December	1st to 10th	Night	83% 5% 6% 5% 2	4580
	11th to 20th	Night	77% 4 5% 9% 5%	5208
	21st to end	Night	73% 4 5% 6% 10% 2	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	28% 25% 32% 12% 3 1	200
	11th to 20th	Day	31% 32% 31% 6% 2 1	200
	21st to end	Day	27% 30% 33% 9% 1	267
February	1st to 10th	Day	39% 35% 23% 2	300
	11th to 20th	Day	35% 32% 27% 6%	381
	21st to end	Day	37% 25% 30% 7% 1	382
March	1st to 10th	Day	32% 24% 30% 11% 3	460
	11th to 20th	Day	32% 26% 28% 11% 3	460
	21st to end	Day	35% 27% 23% 12% 3 1	506
April	1st to 10th	Day	37% 24% 23% 12% 4 1	460
	11th to 20th	Day	34% 23% 22% 14% 5% 2	452
	21st to end	Day	34% 19% 29% 11% 5% 2	460
May	1st to 10th	Day	34% 18% 26% 13% 6% 3	463
	11th to 20th	Day	23% 15% 33% 22% 5% 1	487
	21st to end	Day	20% 18% 31% 20% 10% 1	529
June	1st to 10th	Day	26% 18% 30% 19% 5% 1	490
	11th to 20th	Day	22% 14% 30% 22% 9% 2	490
	21st to end	Day	24% 17% 32% 20% 6% 2	490
July	1st to 10th	Day	19% 9% 32% 26% 11% 3	485
	11th to 20th	Day	18% 10% 33% 27% 11% 2	484
	21st to end	Day	18% 12% 36% 25% 7% 2	532
August	1st to 10th	Day	21% 11% 27% 25% 12% 5%	486
	11th to 20th	Day	20% 9% 28% 23% 13% 6%	479
	21st to end	Day	21% 12% 29% 19% 13% 5%	539
September	1st to 10th	Day	22% 13% 25% 22% 12% 6%	490
	11th to 20th	Day	19% 10% 25% 18% 19% 9%	490
	21st to end	Day	22% 14% 29% 19% 12% 4	490
October	1st to 10th	Day	30% 13% 27% 17% 10% 3	490
	11th to 20th	Day	28% 23% 27% 16% 5% 1	490
	21st to end	Day	36% 20% 25% 17% 2	454
November	1st to 10th	Day	33% 18% 29% 13% 6%	395
	11th to 20th	Day	33% 25% 25% 10% 5% 1	323
	21st to end	Day	40% 24% 29% 8%	200
December	1st to 10th	Day	35% 25% 29% 11% 1	200
	11th to 20th	Day	35% 32% 26% 6% 2	200
	21st to end	Day	33% 28% 31% 6% 1	220
January	1st to 10th	Night	29% 29% 31% 10% 1	800
	11th to 20th	Night	29% 27% 29% 13% 2	800
	21st to end	Night	20% 29% 33% 16% 3	880
February	1st to 10th	Night	26% 30% 34% 10% 1	800
	11th to 20th	Night	26% 28% 32% 12% 1	783
	21st to end	Night	28% 26% 33% 11% 2	629
March	1st to 10th	Night	26% 26% 34% 14% 2	760
	11th to 20th	Night	29% 25% 28% 14% 2 1	760
	21st to end	Night	27% 22% 31% 14% 6% 1	836
April	1st to 10th	Night	27% 22% 32% 17% 2	760
	11th to 20th	Night	28% 22% 27% 15% 6% 1	751
	21st to end	Night	33% 14% 27% 20% 5% 1	710
May	1st to 10th	Night	31% 13% 26% 23% 7%	423
	11th to 20th	Night	20% 14% 32% 26% 7% 1	374
	21st to end	Night	18% 8% 34% 29% 10% 2	411
June	1st to 10th	Night	25% 8% 27% 29% 10% 1	380
	11th to 20th	Night	22% 9% 23% 34% 12%	380
	21st to end	Night	24% 6% 30% 31% 9%	380
July	1st to 10th	Night	13% 7% 25% 39% 15% 1	370
	11th to 20th	Night	14% 4 26% 38% 16% 2	368
	21st to end	Night	16% 6% 23% 41% 12% 1	416
August	1st to 10th	Night	19% 6% 22% 35% 17% 1	423
	11th to 20th	Night	23% 4 22% 28% 20% 2	648
	21st to end	Night	18% 8% 25% 32% 14% 1	836
September	1st to 10th	Night	19% 10% 26% 29% 14% 2	760
	11th to 20th	Night	20% 8% 22% 29% 18% 4	760
	21st to end	Night	24% 11% 24% 25% 15% 1	760
October	1st to 10th	Night	28% 14% 25% 18% 12% 2	760
	11th to 20th	Night	28% 15% 29% 22% 6% 1	760
	21st to end	Night	35% 19% 27% 16% 2	836
November	1st to 10th	Night	28% 20% 30% 16% 6%	780
	11th to 20th	Night	28% 21% 31% 13% 6% 1	800
	21st to end	Night	31% 26% 26% 14% 3	800
December	1st to 10th	Night	33% 26% 28% 11% 3	800
	11th to 20th	Night	30% 28% 27% 13% 2 1	800
	21st to end	Night	33% 28% 26% 12% 2	880

Page generated at 2025-02-18 03:26:27. Version ac07

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