Lincoln
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lincoln clear sky chart from 2005-11-06 to 2024-01-22.

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	14% 9% 4 7% 6% 4 5% 5% 6% 7% 33%	74727
	Night	15% 10% 4 7% 6% 3 5% 5% 5% 7% 33%	75199
Transparency	Day	49% 7% 13% 19% 10% 1	74444
	Night	50% 7% 12% 19% 10% 1	75016
Seeing	Day	18% 11% 26% 25% 15% 6%	13379
	Night	20% 10% 28% 28% 13% 2	22960

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	14% 14% 5% 10% 9% 5% 6% 6% 5% 7% 18%	1517
	11th to 20th	Day	14% 15% 6% 12% 10% 4 6% 6% 5% 5% 18%	1695
	21st to end	Day	13% 13% 6% 15% 10% 6% 7% 5% 4 6% 14%	1791
February	1st to 10th	Day	18% 16% 5% 11% 8% 5% 5% 5% 4 5% 17%	1620
	11th to 20th	Day	12% 15% 7% 12% 8% 4 5% 5% 5% 6% 20%	1573
	21st to end	Day	19% 12% 4 10% 9% 3 5% 5% 4 7% 22%	1398
March	1st to 10th	Day	14% 10% 5% 9% 8% 3 5% 6% 5% 5% 28%	1977
	11th to 20th	Day	12% 13% 5% 8% 8% 3 5% 4 4 5% 33%	1980
	21st to end	Day	18% 10% 3 8% 6% 3 4 5% 5% 6% 32%	2178
April	1st to 10th	Day	17% 9% 5% 7% 6% 4 5% 5% 4 6% 31%	2119
	11th to 20th	Day	17% 8% 4 6% 6% 3 4 4 6% 7% 36%	2189
	21st to end	Day	19% 9% 3 6% 6% 3 5% 4 5% 5% 34%	2340
May	1st to 10th	Day	14% 8% 4 7% 7% 4 5% 5% 5% 8% 35%	2340
	11th to 20th	Day	14% 7% 3 6% 6% 3 6% 4 5% 7% 38%	2432
	21st to end	Day	10% 4 3 5% 5% 3 6% 6% 6% 8% 45%	2725
June	1st to 10th	Day	13% 5% 2 6% 5% 4 4 5% 6% 8% 42%	2520
	11th to 20th	Day	11% 5% 3 6% 5% 4 5% 5% 7% 9% 41%	2520
	21st to end	Day	12% 5% 2 4 5% 3 5% 5% 7% 9% 43%	2520
July	1st to 10th	Day	6% 4 2 4 5% 3 6% 6% 6% 10% 49%	2520
	11th to 20th	Day	11% 5% 3 5% 5% 3 6% 6% 8% 9% 39%	2508
	21st to end	Day	9% 4 2 6% 6% 3 7% 6% 6% 10% 39%	2547
August	1st to 10th	Day	8% 5% 2 5% 5% 4 6% 6% 7% 10% 42%	2327
	11th to 20th	Day	9% 4 2 6% 6% 4 5% 6% 8% 10% 39%	2303
	21st to end	Day	11% 5% 3 5% 5% 2 4 5% 6% 9% 45%	2471
September	1st to 10th	Day	13% 6% 3 6% 5% 3 5% 5% 6% 8% 40%	2160
	11th to 20th	Day	10% 5% 2 5% 5% 3 5% 4 5% 8% 48%	2048
	21st to end	Day	14% 5% 3 6% 7% 3 5% 5% 6% 8% 37%	1945
October	1st to 10th	Day	19% 7% 3 7% 5% 3 5% 4 5% 7% 35%	1800
	11th to 20th	Day	17% 11% 4 8% 7% 3 5% 5% 5% 6% 31%	1800
	21st to end	Day	24% 12% 3 7% 6% 3 4 4 4 6% 24%	1980
November	1st to 10th	Day	13% 9% 4 8% 6% 4 4 5% 5% 7% 35%	1646
	11th to 20th	Day	13% 11% 5% 8% 8% 4 6% 5% 5% 7% 30%	1520
	21st to end	Day	20% 13% 4 7% 7% 3 4 5% 6% 6% 26%	1520
December	1st to 10th	Day	17% 13% 6% 9% 8% 5% 5% 5% 6% 6% 21%	1520
	11th to 20th	Day	17% 14% 6% 9% 8% 4 6% 5% 6% 6% 20%	1906
	21st to end	Day	27% 18% 7% 11% 7% 4 4 4 4 4 11%	2772
January	1st to 10th	Night	15% 15% 5% 10% 8% 4 6% 4 5% 5% 22%	2649
	11th to 20th	Night	18% 14% 6% 11% 9% 5% 5% 5% 4 5% 17%	2482
	21st to end	Night	13% 14% 5% 10% 9% 4 6% 5% 5% 7% 21%	2599
February	1st to 10th	Night	16% 15% 5% 11% 8% 3 6% 4 5% 6% 22%	2340
	11th to 20th	Night	15% 13% 6% 10% 7% 4 5% 5% 5% 7% 26%	2273
	21st to end	Night	17% 13% 5% 9% 8% 4 5% 5% 5% 6% 24%	1852
March	1st to 10th	Night	14% 9% 4 8% 8% 5% 5% 5% 6% 6% 31%	1970
	11th to 20th	Night	17% 10% 5% 8% 6% 2 5% 4 4 6% 33%	1979
	21st to end	Night	16% 10% 4 8% 6% 3 5% 5% 4 5% 36%	2178
April	1st to 10th	Night	17% 9% 4 8% 6% 3 4 5% 5% 7% 33%	1840
	11th to 20th	Night	17% 8% 2 6% 5% 3 5% 5% 5% 6% 38%	1736
	21st to end	Night	16% 8% 4 6% 5% 3 6% 5% 6% 6% 35%	1620
May	1st to 10th	Night	15% 9% 4 6% 5% 3 4 5% 5% 8% 37%	1620
	11th to 20th	Night	13% 5% 3 6% 6% 3 4 5% 5% 8% 41%	1458
	21st to end	Night	10% 7% 2 5% 5% 3 4 4 5% 7% 49%	1550
June	1st to 10th	Night	10% 6% 3 6% 6% 4 6% 5% 8% 8% 38%	1440
	11th to 20th	Night	9% 5% 3 6% 7% 4 5% 5% 5% 8% 44%	1440
	21st to end	Night	11% 5% 2 6% 4 3 4 5% 6% 8% 45%	1440
July	1st to 10th	Night	5% 4 2 5% 5% 3 4 4 5% 8% 56%	1440
	11th to 20th	Night	9% 4 2 6% 5% 2 4 5% 7% 9% 47%	1448
	21st to end	Night	9% 3 2 5% 5% 2 5% 5% 7% 9% 48%	1771
August	1st to 10th	Night	8% 4 2 5% 5% 4 4 6% 8% 8% 47%	1611
	11th to 20th	Night	7% 5% 2 4 5% 3 4 6% 7% 9% 47%	1598
	21st to end	Night	8% 5% 2 4 5% 3 5% 5% 6% 9% 48%	1867
September	1st to 10th	Night	13% 5% 2 6% 5% 4 4 5% 5% 7% 44%	1800
	11th to 20th	Night	11% 5% 2 4 4 3 4 4 4 8% 52%	1908
	21st to end	Night	14% 6% 3 7% 6% 3 4 4 5% 7% 39%	2014
October	1st to 10th	Night	18% 7% 3 6% 5% 3 4 4 5% 6% 39%	2160
	11th to 20th	Night	19% 10% 3 7% 5% 3 4 4 5% 7% 32%	2160
	21st to end	Night	24% 9% 4 6% 6% 3 5% 5% 5% 6% 27%	2376
November	1st to 10th	Night	15% 8% 3 6% 6% 3 4 5% 5% 6% 39%	2428
	11th to 20th	Night	15% 9% 4 7% 6% 4 5% 5% 5% 8% 31%	2660
	21st to end	Night	18% 11% 4 7% 6% 4 6% 4 6% 6% 28%	2660
December	1st to 10th	Night	18% 13% 6% 9% 6% 4 5% 5% 5% 6% 22%	2660
	11th to 20th	Night	14% 17% 6% 9% 6% 4 5% 5% 5% 5% 23%	3288
	21st to end	Night	28% 15% 6% 10% 7% 3 5% 4 5% 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	63% 11% 9% 12% 4	1518
	11th to 20th	Day	69% 8% 10% 10% 3	1695
	21st to end	Day	70% 8% 9% 9% 4	1791
February	1st to 10th	Day	69% 7% 9% 11% 4 1	1620
	11th to 20th	Day	64% 7% 10% 13% 4	1582
	21st to end	Day	62% 7% 12% 13% 6% 1	1398
March	1st to 10th	Day	56% 7% 14% 16% 6% 1	1980
	11th to 20th	Day	53% 6% 11% 17% 11% 2	1980
	21st to end	Day	53% 6% 9% 21% 10% 2	2178
April	1st to 10th	Day	54% 5% 12% 17% 11% 1	2119
	11th to 20th	Day	47% 6% 12% 19% 14% 2	2189
	21st to end	Day	50% 6% 12% 17% 12% 2	2340
May	1st to 10th	Day	47% 5% 12% 22% 12% 2	2340
	11th to 20th	Day	45% 7% 12% 21% 13% 1	2436
	21st to end	Day	34% 8% 17% 24% 14% 2	2725
June	1st to 10th	Day	39% 8% 12% 23% 15% 2	2520
	11th to 20th	Day	38% 6% 15% 25% 14% 1	2520
	21st to end	Day	36% 8% 15% 25% 15% 1	2520
July	1st to 10th	Day	29% 8% 15% 27% 19% 3	2450
	11th to 20th	Day	36% 8% 18% 25% 12% 1	2433
	21st to end	Day	38% 9% 16% 23% 13% 1	2405
August	1st to 10th	Day	34% 8% 18% 26% 12% 2	2314
	11th to 20th	Day	36% 10% 18% 24% 11% 1	2303
	21st to end	Day	36% 6% 15% 29% 14% 1	2471
September	1st to 10th	Day	39% 8% 16% 23% 12% 1	2160
	11th to 20th	Day	34% 7% 15% 29% 15%	2048
	21st to end	Day	43% 7% 16% 24% 9% 1	1945
October	1st to 10th	Day	49% 6% 14% 18% 12% 1	1800
	11th to 20th	Day	54% 6% 13% 19% 8% 1	1800
	21st to end	Day	61% 7% 12% 14% 5% 1	1980
November	1st to 10th	Day	48% 8% 14% 21% 8% 1	1646
	11th to 20th	Day	51% 8% 16% 15% 10%	1520
	21st to end	Day	57% 8% 16% 15% 4	1520
December	1st to 10th	Day	63% 8% 15% 12% 2	1520
	11th to 20th	Day	63% 10% 14% 10% 4	1906
	21st to end	Day	75% 8% 9% 6% 1	2772
January	1st to 10th	Night	63% 9% 10% 12% 5%	2649
	11th to 20th	Night	67% 10% 10% 9% 3	2482
	21st to end	Night	62% 8% 11% 14% 4 1	2599
February	1st to 10th	Night	64% 7% 10% 14% 5% 1	2340
	11th to 20th	Night	58% 7% 12% 16% 6%	2275
	21st to end	Night	60% 8% 11% 14% 7%	1852
March	1st to 10th	Night	53% 7% 12% 19% 8% 1	1980
	11th to 20th	Night	53% 5% 11% 19% 11% 2	1980
	21st to end	Night	50% 5% 8% 21% 14% 2	2178
April	1st to 10th	Night	51% 5% 10% 20% 11% 1	1840
	11th to 20th	Night	47% 6% 10% 19% 16% 2	1736
	21st to end	Night	47% 7% 11% 18% 15% 2	1620
May	1st to 10th	Night	45% 6% 9% 22% 14% 4	1620
	11th to 20th	Night	41% 7% 12% 24% 14% 3	1459
	21st to end	Night	35% 7% 14% 25% 18% 3	1551
June	1st to 10th	Night	39% 10% 11% 22% 17% 2	1440
	11th to 20th	Night	38% 6% 12% 23% 18% 2	1440
	21st to end	Night	36% 6% 14% 25% 17% 2	1440
July	1st to 10th	Night	28% 6% 12% 26% 24% 4	1400
	11th to 20th	Night	31% 8% 13% 29% 18% 2	1400
	21st to end	Night	32% 8% 17% 24% 17% 3	1672
August	1st to 10th	Night	31% 10% 16% 29% 14% 2	1600
	11th to 20th	Night	31% 9% 16% 30% 13% 1	1598
	21st to end	Night	32% 7% 14% 29% 15% 2	1867
September	1st to 10th	Night	38% 6% 15% 24% 14% 2	1800
	11th to 20th	Night	31% 6% 12% 32% 18% 1	1908
	21st to end	Night	43% 8% 12% 23% 13% 1	2014
October	1st to 10th	Night	45% 7% 11% 22% 14% 1	2160
	11th to 20th	Night	51% 7% 13% 19% 9% 1	2160
	21st to end	Night	56% 6% 12% 16% 9% 1	2376
November	1st to 10th	Night	44% 7% 12% 23% 12% 1	2428
	11th to 20th	Night	50% 8% 14% 18% 9% 1	2660
	21st to end	Night	55% 9% 15% 16% 4	2660
December	1st to 10th	Night	61% 10% 13% 12% 3	2660
	11th to 20th	Night	61% 8% 13% 13% 4	3288
	21st to end	Night	73% 8% 11% 6% 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	19% 21% 36% 16% 8% 1	180
	11th to 20th	Day	24% 19% 36% 16% 5% 2	263
	21st to end	Day	19% 20% 32% 23% 4 1	267
February	1st to 10th	Day	25% 19% 43% 13% 1	240
	11th to 20th	Day	25% 20% 39% 15% 1	240
	21st to end	Day	28% 22% 33% 15% 2	220
March	1st to 10th	Day	21% 15% 35% 23% 7%	420
	11th to 20th	Day	20% 15% 34% 23% 6% 1	420
	21st to end	Day	27% 13% 28% 22% 9% 1	462
April	1st to 10th	Day	18% 14% 31% 26% 9% 2	420
	11th to 20th	Day	23% 16% 24% 23% 11% 4	412
	21st to end	Day	25% 7% 30% 25% 10% 2	420
May	1st to 10th	Day	22% 8% 27% 26% 12% 4	423
	11th to 20th	Day	18% 9% 19% 28% 21% 6%	447
	21st to end	Day	12% 6% 21% 31% 21% 9%	485
June	1st to 10th	Day	13% 8% 24% 36% 15% 4	450
	11th to 20th	Day	14% 7% 23% 30% 23% 4	450
	21st to end	Day	14% 5% 22% 33% 20% 5%	450
July	1st to 10th	Day	10% 2 13% 32% 31% 12%	445
	11th to 20th	Day	15% 4 18% 30% 23% 10%	444
	21st to end	Day	9% 3 22% 36% 22% 9%	488
August	1st to 10th	Day	10% 2 16% 33% 25% 14%	446
	11th to 20th	Day	10% 6% 19% 28% 25% 13%	439
	21st to end	Day	14% 5% 19% 29% 21% 12%	495
September	1st to 10th	Day	14% 6% 20% 27% 22% 11%	450
	11th to 20th	Day	10% 7% 18% 23% 27% 16%	450
	21st to end	Day	16% 10% 25% 24% 15% 10%	450
October	1st to 10th	Day	21% 10% 24% 20% 17% 8%	450
	11th to 20th	Day	20% 16% 30% 22% 9% 2	450
	21st to end	Day	33% 14% 24% 20% 9%	495
November	1st to 10th	Day	17% 21% 31% 20% 9% 3	290
	11th to 20th	Day	21% 23% 28% 19% 7% 2	180
	21st to end	Day	27% 15% 37% 17% 4	180
December	1st to 10th	Day	24% 19% 38% 12% 5% 1	180
	11th to 20th	Day	24% 27% 33% 13% 3	180
	21st to end	Day	24% 17% 39% 18% 3	198
January	1st to 10th	Night	26% 17% 33% 17% 7%	760
	11th to 20th	Night	27% 18% 32% 19% 4	760
	21st to end	Night	18% 14% 38% 24% 6%	800
February	1st to 10th	Night	26% 18% 35% 18% 3	720
	11th to 20th	Night	21% 16% 34% 26% 4	703
	21st to end	Night	23% 15% 36% 24% 2	592
March	1st to 10th	Night	19% 13% 33% 27% 7%	720
	11th to 20th	Night	25% 13% 31% 23% 8% 1	720
	21st to end	Night	20% 9% 30% 30% 10% 1	792
April	1st to 10th	Night	22% 12% 30% 30% 6%	720
	11th to 20th	Night	20% 9% 32% 26% 11% 2	672
	21st to end	Night	20% 6% 29% 34% 12%	540
May	1st to 10th	Night	20% 5% 23% 31% 19% 2	540
	11th to 20th	Night	15% 5% 24% 39% 16% 1	397
	21st to end	Night	14% 4 21% 34% 24% 3	389
June	1st to 10th	Night	14% 2 31% 34% 18% 1	360
	11th to 20th	Night	13% 4 24% 37% 22%	360
	21st to end	Night	11% 4 21% 47% 17% 1	360
July	1st to 10th	Night	7% 3 17% 46% 26% 2	350
	11th to 20th	Night	10% 3 21% 42% 21% 3	356
	21st to end	Night	10% 3 16% 44% 24% 3	591
August	1st to 10th	Night	9% 2 14% 38% 33% 4	537
	11th to 20th	Night	8% 3 16% 31% 37% 4	534
	21st to end	Night	11% 2 18% 35% 29% 4	679
September	1st to 10th	Night	14% 5% 16% 35% 24% 6%	720
	11th to 20th	Night	12% 5% 17% 30% 29% 6%	720
	21st to end	Night	16% 6% 21% 29% 22% 6%	720
October	1st to 10th	Night	19% 7% 24% 28% 19% 3	720
	11th to 20th	Night	24% 11% 29% 26% 9% 1	720
	21st to end	Night	30% 11% 27% 26% 7%	792
November	1st to 10th	Night	20% 10% 28% 28% 11% 2	740
	11th to 20th	Night	20% 15% 33% 21% 9% 2	760
	21st to end	Night	24% 13% 35% 21% 7% 1	760
December	1st to 10th	Night	28% 18% 32% 17% 6%	760
	11th to 20th	Night	24% 18% 34% 19% 5%	760
	21st to end	Night	28% 15% 33% 21% 3	836

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