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 2024-01-31.

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	19% 12% 5% 8% 6% 3 4 4 5% 6% 27%	74893
	Night	18% 13% 6% 9% 6% 3 4 4 4 5% 26%	75229
Transparency	Day	58% 6% 10% 16% 9% 1	74598
	Night	60% 6% 10% 15% 8% 1	75058
Seeing	Day	27% 19% 29% 16% 7% 2	13580
	Night	26% 19% 28% 19% 7% 1	22835

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% 21% 10% 15% 9% 4 4 4 3 3 14%	1517
	11th to 20th	Day	15% 21% 8% 12% 11% 4 3 3 4 4 17%	1520
	21st to end	Day	11% 17% 10% 15% 10% 5% 6% 4 4 4 15%	1751
February	1st to 10th	Day	14% 19% 7% 17% 10% 5% 6% 4 3 4 12%	1620
	11th to 20th	Day	13% 16% 10% 15% 9% 3 4 4 2 4 18%	1645
	21st to end	Day	15% 18% 9% 13% 8% 4 4 4 3 4 16%	1480
March	1st to 10th	Day	14% 14% 10% 14% 8% 3 4 3 4 4 23%	1797
	11th to 20th	Day	16% 16% 8% 10% 6% 3 3 4 4 4 25%	1939
	21st to end	Day	20% 14% 6% 7% 6% 2 3 3 3 5% 30%	2322
April	1st to 10th	Day	20% 15% 7% 6% 4 2 3 3 4 5% 29%	2160
	11th to 20th	Day	18% 13% 5% 7% 5% 2 4 4 4 5% 33%	2134
	21st to end	Day	23% 15% 3 7% 5% 3 3 4 5% 5% 28%	2205
May	1st to 10th	Day	22% 13% 4 7% 5% 3 4 4 4 5% 30%	2493
	11th to 20th	Day	19% 9% 4 5% 5% 3 4 5% 5% 7% 34%	2478
	21st to end	Day	19% 8% 3 6% 6% 3 5% 5% 5% 7% 34%	2725
June	1st to 10th	Day	26% 7% 3 5% 6% 3 6% 5% 5% 7% 28%	2520
	11th to 20th	Day	23% 7% 3 5% 5% 3 4 5% 6% 8% 30%	2520
	21st to end	Day	22% 7% 3 6% 6% 3 5% 5% 6% 7% 29%	2520
July	1st to 10th	Day	18% 6% 3 5% 4 3 4 5% 6% 8% 36%	2520
	11th to 20th	Day	18% 6% 3 6% 6% 4 6% 5% 7% 8% 33%	2520
	21st to end	Day	18% 6% 3 6% 6% 4 6% 6% 7% 8% 30%	2744
August	1st to 10th	Day	18% 6% 3 6% 6% 4 4 6% 6% 8% 34%	2462
	11th to 20th	Day	18% 8% 2 6% 6% 4 5% 6% 6% 8% 30%	2206
	21st to end	Day	19% 7% 2 5% 6% 3 5% 5% 5% 8% 34%	2376
September	1st to 10th	Day	20% 5% 2 5% 4 4 5% 5% 6% 7% 36%	2160
	11th to 20th	Day	20% 7% 3 5% 4 3 4 4 5% 6% 42%	2127
	21st to end	Day	20% 9% 3 4 5% 3 5% 5% 5% 6% 35%	1978
October	1st to 10th	Day	28% 11% 3 6% 6% 3 3 4 3 4 30%	1800
	11th to 20th	Day	22% 15% 4 6% 5% 2 4 5% 5% 7% 26%	1800
	21st to end	Day	28% 16% 5% 6% 5% 3 4 3 4 4 22%	1828
November	1st to 10th	Day	17% 16% 5% 7% 6% 3 4 5% 4 5% 27%	1671
	11th to 20th	Day	17% 19% 7% 8% 6% 3 4 3 5% 5% 25%	1637
	21st to end	Day	18% 20% 8% 11% 6% 4 5% 3 3 3 19%	1520
December	1st to 10th	Day	18% 25% 11% 11% 6% 3 4 3 3 3 12%	1520
	11th to 20th	Day	18% 16% 12% 16% 8% 3 3 3 3 4 14%	1906
	21st to end	Day	21% 21% 8% 15% 6% 3 3 2 3 3 14%	2772
January	1st to 10th	Night	15% 20% 10% 14% 11% 4 5% 3 2 3 13%	2649
	11th to 20th	Night	15% 18% 10% 14% 10% 4 5% 4 3 3 15%	2660
	21st to end	Night	11% 15% 10% 15% 9% 4 7% 4 4 4 17%	2830
February	1st to 10th	Night	15% 17% 9% 17% 12% 4 5% 3 3 3 12%	2340
	11th to 20th	Night	12% 13% 10% 16% 11% 5% 5% 4 4 5% 17%	2199
	21st to end	Night	14% 14% 8% 13% 9% 6% 4 4 3 6% 18%	1776
March	1st to 10th	Night	15% 13% 7% 13% 10% 3 5% 4 3 4 24%	2150
	11th to 20th	Night	14% 17% 7% 10% 6% 3 4 3 4 5% 27%	2015
	21st to end	Night	18% 14% 6% 7% 6% 2 3 4 4 5% 31%	2033
April	1st to 10th	Night	20% 15% 6% 7% 5% 3 4 3 4 4 27%	1800
	11th to 20th	Night	19% 14% 5% 5% 6% 3 3 5% 6% 5% 29%	1775
	21st to end	Night	22% 14% 3 6% 4 3 3 3 5% 5% 31%	1753
May	1st to 10th	Night	24% 10% 4 5% 5% 4 4 4 4 5% 31%	1481
	11th to 20th	Night	14% 11% 3 5% 5% 3 4 4 5% 8% 36%	1415
	21st to end	Night	17% 6% 3 5% 5% 4 6% 5% 6% 7% 37%	1550
June	1st to 10th	Night	23% 6% 3 5% 6% 2 5% 5% 6% 6% 33%	1440
	11th to 20th	Night	22% 7% 2 4 5% 3 4 4 5% 8% 37%	1440
	21st to end	Night	20% 7% 3 6% 5% 3 5% 5% 6% 8% 34%	1440
July	1st to 10th	Night	15% 5% 3 4 5% 3 6% 5% 5% 7% 43%	1440
	11th to 20th	Night	14% 5% 2 5% 5% 4 4 5% 5% 8% 43%	1440
	21st to end	Night	13% 7% 2 5% 5% 3 5% 4 6% 8% 42%	1574
August	1st to 10th	Night	16% 5% 2 5% 5% 3 4 5% 6% 8% 40%	1474
	11th to 20th	Night	18% 7% 3 5% 4 3 4 5% 5% 7% 38%	1677
	21st to end	Night	16% 7% 2 5% 4 3 3 5% 5% 7% 42%	1980
September	1st to 10th	Night	18% 7% 3 6% 5% 3 5% 4 4 6% 41%	1800
	11th to 20th	Night	17% 8% 3 4 4 2 3 4 3 6% 47%	1831
	21st to end	Night	21% 7% 2 5% 4 2 4 5% 5% 7% 38%	1980
October	1st to 10th	Night	25% 11% 3 6% 5% 3 4 4 4 5% 30%	2160
	11th to 20th	Night	21% 13% 3 6% 5% 3 5% 4 4 6% 29%	2160
	21st to end	Night	27% 17% 4 6% 6% 3 3 4 4 4 21%	2527
November	1st to 10th	Night	18% 16% 5% 7% 5% 3 4 4 3 5% 28%	2407
	11th to 20th	Night	18% 16% 6% 9% 6% 3 4 4 4 6% 25%	2541
	21st to end	Night	18% 19% 8% 12% 7% 3 4 3 3 5% 18%	2660
December	1st to 10th	Night	18% 24% 11% 14% 6% 2 4 3 4 4 12%	2660
	11th to 20th	Night	18% 19% 10% 14% 7% 3 4 3 3 3 16%	3288
	21st to end	Night	23% 19% 7% 16% 6% 2 3 3 3 5% 12%	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	75% 4 7% 9% 5%	1518
	11th to 20th	Day	73% 3 6% 9% 6% 3	1520
	21st to end	Day	73% 5% 6% 9% 5% 2	1751
February	1st to 10th	Day	78% 4 7% 8% 3 1	1620
	11th to 20th	Day	70% 4 7% 9% 8% 1	1654
	21st to end	Day	71% 6% 7% 9% 7%	1480
March	1st to 10th	Day	65% 5% 9% 12% 8% 2	1800
	11th to 20th	Day	61% 6% 10% 11% 10% 2	1939
	21st to end	Day	58% 3 7% 14% 14% 3	2322
April	1st to 10th	Day	58% 4 8% 17% 11% 2	2160
	11th to 20th	Day	53% 6% 7% 19% 13% 1	2134
	21st to end	Day	59% 6% 8% 14% 11% 3	2205
May	1st to 10th	Day	57% 5% 8% 17% 11% 2	2493
	11th to 20th	Day	48% 7% 10% 22% 11% 2	2482
	21st to end	Day	49% 8% 14% 19% 9% 1	2725
June	1st to 10th	Day	55% 8% 12% 15% 10% 1	2520
	11th to 20th	Day	50% 7% 12% 21% 8% 1	2520
	21st to end	Day	53% 8% 13% 18% 7% 1	2520
July	1st to 10th	Day	44% 8% 13% 24% 11%	2450
	11th to 20th	Day	45% 9% 15% 24% 6%	2445
	21st to end	Day	49% 9% 12% 19% 10%	2591
August	1st to 10th	Day	46% 8% 15% 21% 9%	2448
	11th to 20th	Day	49% 9% 14% 20% 7%	2206
	21st to end	Day	47% 8% 13% 23% 8% 1	2376
September	1st to 10th	Day	45% 8% 12% 24% 11% 1	2160
	11th to 20th	Day	43% 6% 10% 25% 14% 1	2127
	21st to end	Day	49% 6% 11% 21% 12% 1	1978
October	1st to 10th	Day	60% 5% 8% 17% 10% 1	1800
	11th to 20th	Day	57% 7% 14% 15% 5% 1	1800
	21st to end	Day	66% 7% 9% 10% 7% 1	1828
November	1st to 10th	Day	59% 7% 11% 14% 9%	1671
	11th to 20th	Day	62% 7% 8% 12% 8% 3	1637
	21st to end	Day	70% 6% 11% 8% 5%	1520
December	1st to 10th	Day	78% 5% 8% 6% 2 1	1520
	11th to 20th	Day	76% 4 6% 8% 4	1906
	21st to end	Day	78% 4 4 6% 8%	2772
January	1st to 10th	Night	78% 4 6% 7% 5%	2649
	11th to 20th	Night	76% 4 6% 7% 4 2	2660
	21st to end	Night	69% 5% 7% 10% 6% 2	2830
February	1st to 10th	Night	78% 5% 6% 6% 5% 1	2340
	11th to 20th	Night	71% 5% 7% 10% 6%	2201
	21st to end	Night	68% 6% 9% 11% 6% 1	1776
March	1st to 10th	Night	64% 5% 9% 13% 7% 1	2160
	11th to 20th	Night	60% 6% 9% 15% 8% 1	2016
	21st to end	Night	57% 4 9% 15% 12% 3	2033
April	1st to 10th	Night	60% 5% 9% 17% 7% 2	1800
	11th to 20th	Night	55% 7% 9% 18% 11%	1775
	21st to end	Night	54% 6% 9% 17% 11% 2	1753
May	1st to 10th	Night	56% 6% 8% 14% 14% 2	1481
	11th to 20th	Night	46% 7% 10% 22% 13% 2	1416
	21st to end	Night	45% 9% 14% 20% 11% 2	1551
June	1st to 10th	Night	48% 8% 14% 20% 9% 1	1440
	11th to 20th	Night	46% 7% 14% 21% 11% 1	1440
	21st to end	Night	47% 8% 13% 22% 9%	1440
July	1st to 10th	Night	38% 8% 15% 23% 14% 2	1400
	11th to 20th	Night	38% 7% 16% 28% 9%	1392
	21st to end	Night	40% 7% 17% 26% 9% 1	1486
August	1st to 10th	Night	40% 10% 17% 26% 7%	1464
	11th to 20th	Night	44% 8% 15% 23% 10%	1677
	21st to end	Night	41% 8% 14% 28% 9%	1980
September	1st to 10th	Night	44% 8% 11% 25% 11% 1	1800
	11th to 20th	Night	39% 6% 12% 29% 14% 1	1831
	21st to end	Night	44% 8% 10% 24% 12% 2	1980
October	1st to 10th	Night	56% 6% 11% 15% 11% 1	2160
	11th to 20th	Night	55% 8% 12% 18% 6% 1	2160
	21st to end	Night	66% 7% 10% 9% 7% 1	2527
November	1st to 10th	Night	59% 6% 10% 14% 9% 2	2407
	11th to 20th	Night	60% 7% 9% 13% 7% 3	2541
	21st to end	Night	70% 6% 9% 10% 5% 1	2660
December	1st to 10th	Night	77% 6% 8% 6% 3	2660
	11th to 20th	Night	74% 6% 7% 8% 5%	3288
	21st to end	Night	76% 5% 6% 7% 6%	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	27% 23% 33% 13% 3 1	180
	11th to 20th	Day	32% 30% 29% 6% 2 1	180
	21st to end	Day	23% 29% 35% 11% 2	237
February	1st to 10th	Day	40% 37% 21% 2	240
	11th to 20th	Day	33% 32% 29% 5%	312
	21st to end	Day	37% 25% 29% 7% 1	346
March	1st to 10th	Day	30% 26% 30% 12% 2	420
	11th to 20th	Day	31% 26% 28% 12% 3	420
	21st to end	Day	36% 25% 22% 13% 3 2	462
April	1st to 10th	Day	35% 25% 24% 12% 4 1	420
	11th to 20th	Day	32% 23% 23% 16% 6% 2	412
	21st to end	Day	34% 19% 30% 11% 5% 2	420
May	1st to 10th	Day	34% 19% 25% 12% 6% 3	423
	11th to 20th	Day	25% 16% 33% 21% 4 2	447
	21st to end	Day	21% 17% 31% 19% 11% 1	485
June	1st to 10th	Day	26% 18% 31% 19% 5% 1	450
	11th to 20th	Day	22% 14% 30% 21% 10% 2	450
	21st to end	Day	23% 15% 33% 20% 6% 2	450
July	1st to 10th	Day	20% 9% 30% 27% 11% 3	445
	11th to 20th	Day	18% 9% 32% 27% 11% 2	444
	21st to end	Day	18% 12% 38% 24% 6% 2	488
August	1st to 10th	Day	19% 11% 27% 26% 12% 5%	446
	11th to 20th	Day	19% 8% 29% 24% 13% 6%	439
	21st to end	Day	21% 13% 30% 19% 13% 5%	495
September	1st to 10th	Day	23% 12% 25% 22% 13% 6%	450
	11th to 20th	Day	20% 11% 27% 18% 17% 7%	450
	21st to end	Day	22% 14% 30% 18% 11% 4	450
October	1st to 10th	Day	31% 14% 26% 16% 11% 4	450
	11th to 20th	Day	28% 24% 27% 16% 5% 1	450
	21st to end	Day	37% 20% 24% 16% 2	419
November	1st to 10th	Day	33% 18% 29% 14% 7%	365
	11th to 20th	Day	34% 26% 26% 9% 4 1	297
	21st to end	Day	36% 26% 30% 9%	180
December	1st to 10th	Day	34% 24% 30% 10% 1	180
	11th to 20th	Day	33% 33% 27% 6% 2	180
	21st to end	Day	34% 30% 32% 3 1 1	198
January	1st to 10th	Night	29% 27% 32% 11% 1	760
	11th to 20th	Night	30% 27% 29% 13% 2	760
	21st to end	Night	20% 28% 33% 16% 3	835
February	1st to 10th	Night	26% 29% 35% 9% 1	720
	11th to 20th	Night	25% 29% 33% 12% 2	703
	21st to end	Night	28% 26% 34% 11% 2	592
March	1st to 10th	Night	25% 26% 34% 14% 1	720
	11th to 20th	Night	29% 25% 29% 14% 3 1	720
	21st to end	Night	27% 22% 31% 14% 6% 1	792
April	1st to 10th	Night	27% 22% 32% 17% 2	720
	11th to 20th	Night	27% 22% 28% 16% 7% 1	711
	21st to end	Night	33% 14% 27% 20% 5% 1	673
May	1st to 10th	Night	30% 12% 26% 23% 7%	401
	11th to 20th	Night	21% 14% 32% 26% 7% 1	354
	21st to end	Night	18% 8% 34% 29% 10% 2	389
June	1st to 10th	Night	26% 8% 28% 28% 11% 1	360
	11th to 20th	Night	23% 9% 23% 33% 12%	360
	21st to end	Night	23% 5% 31% 33% 9%	360
July	1st to 10th	Night	13% 7% 25% 39% 15% 1	350
	11th to 20th	Night	14% 4 25% 38% 16% 2	348
	21st to end	Night	16% 7% 24% 41% 12% 1	394
August	1st to 10th	Night	18% 5% 22% 36% 18% 1	400
	11th to 20th	Night	23% 4 22% 29% 20% 2	613
	21st to end	Night	18% 8% 26% 32% 14% 1	792
September	1st to 10th	Night	19% 10% 26% 30% 14% 2	720
	11th to 20th	Night	21% 8% 23% 28% 16% 3	720
	21st to end	Night	24% 11% 24% 25% 15% 1	720
October	1st to 10th	Night	29% 14% 26% 18% 12% 2	720
	11th to 20th	Night	27% 16% 30% 21% 5% 1	720
	21st to end	Night	36% 19% 27% 16% 2	792
November	1st to 10th	Night	28% 19% 31% 16% 6%	740
	11th to 20th	Night	28% 22% 31% 12% 6% 1	760
	21st to end	Night	31% 26% 27% 14% 3	760
December	1st to 10th	Night	33% 26% 28% 11% 2	760
	11th to 20th	Night	28% 29% 28% 12% 2 1	760
	21st to end	Night	33% 29% 26% 11% 1	836

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