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 2026-05-02.

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	13% 10% 4 9% 6% 5% 5% 4 5% 7% 32%	131966
	Night	14% 10% 4 9% 6% 5% 5% 4 5% 7% 32%	130501
Transparency	Day	49% 6% 13% 20% 11% 1	135561
	Night	50% 6% 12% 19% 11% 1	134992
Seeing	Day	19% 12% 27% 24% 14% 5%	16302
	Night	20% 11% 28% 27% 13% 2	25869

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	13% 16% 5% 13% 6% 5% 5% 4 5% 6% 23%	4661
	11th to 20th	Day	9% 21% 7% 18% 8% 7% 5% 3 4 5% 12%	5204
	21st to end	Day	14% 14% 6% 16% 10% 8% 5% 3 4 5% 16%	5780
February	1st to 10th	Day	16% 17% 4 13% 7% 6% 5% 4 5% 5% 19%	1890
	11th to 20th	Day	12% 16% 6% 13% 7% 6% 4 4 5% 6% 21%	1843
	21st to end	Day	17% 14% 4 11% 7% 4 5% 4 4 7% 22%	1636
March	1st to 10th	Day	16% 10% 5% 11% 6% 4 4 4 5% 5% 29%	5042
	11th to 20th	Day	10% 13% 5% 10% 6% 5% 5% 4 5% 7% 31%	5090
	21st to end	Day	16% 11% 3 11% 6% 5% 4 3 4 5% 32%	5586
April	1st to 10th	Day	17% 11% 4 8% 5% 5% 4 4 4 6% 31%	2473
	11th to 20th	Day	17% 10% 3 8% 5% 4 4 3 6% 7% 34%	2559
	21st to end	Day	18% 9% 2 7% 5% 4 5% 4 5% 5% 35%	2730
May	1st to 10th	Day	17% 9% 4 8% 5% 5% 4 4 5% 6% 33%	5901
	11th to 20th	Day	14% 11% 4 9% 5% 5% 5% 4 5% 7% 32%	6216
	21st to end	Day	15% 7% 3 7% 4 5% 5% 4 5% 7% 38%	6949
June	1st to 10th	Day	13% 6% 2 7% 5% 5% 5% 4 6% 8% 40%	2800
	11th to 20th	Day	10% 5% 3 7% 5% 6% 5% 4 7% 9% 39%	2800
	21st to end	Day	11% 5% 2 5% 4 4 4 4 8% 9% 42%	2800
July	1st to 10th	Day	7% 5% 2 6% 5% 5% 6% 5% 7% 10% 42%	6360
	11th to 20th	Day	8% 5% 2 6% 4 5% 6% 5% 7% 9% 43%	6320
	21st to end	Day	7% 4 2 6% 5% 4 5% 4 6% 9% 48%	6424
August	1st to 10th	Day	16% 7% 2 6% 4 5% 5% 4 6% 8% 38%	4234
	11th to 20th	Day	11% 6% 2 8% 5% 5% 6% 5% 8% 10% 35%	4174
	21st to end	Day	8% 5% 2 7% 4 4 5% 4 6% 9% 45%	4482
September	1st to 10th	Day	12% 6% 3 6% 4 4 5% 4 6% 8% 41%	2400
	11th to 20th	Day	9% 6% 2 5% 5% 4 5% 3 5% 8% 49%	2275
	21st to end	Day	14% 6% 3 8% 6% 5% 5% 4 7% 8% 35%	2161
October	1st to 10th	Day	18% 7% 3 7% 4 5% 5% 3 6% 7% 37%	2000
	11th to 20th	Day	16% 11% 3 9% 5% 4 4 4 5% 6% 32%	2000
	21st to end	Day	23% 11% 3 9% 5% 5% 5% 4 4 6% 25%	2200
November	1st to 10th	Day	13% 9% 3 9% 6% 5% 4 4 5% 7% 34%	1822
	11th to 20th	Day	12% 12% 4 9% 7% 6% 5% 3 5% 7% 30%	1680
	21st to end	Day	19% 14% 4 8% 7% 4 4 5% 6% 6% 24%	1680
December	1st to 10th	Day	18% 15% 5% 11% 6% 7% 5% 5% 6% 6% 16%	2680
	11th to 20th	Day	17% 15% 5% 9% 6% 5% 5% 3 5% 5% 24%	3066
	21st to end	Day	23% 16% 6% 13% 7% 6% 5% 4 4 5% 11%	4048
January	1st to 10th	Night	14% 15% 5% 11% 7% 5% 5% 4 5% 6% 24%	8234
	11th to 20th	Night	9% 15% 6% 15% 9% 6% 6% 4 5% 5% 19%	7664
	21st to end	Night	15% 14% 5% 13% 7% 6% 5% 4 5% 6% 21%	8401
February	1st to 10th	Night	15% 15% 4 11% 6% 4 5% 3 5% 6% 24%	2730
	11th to 20th	Night	14% 13% 5% 11% 6% 5% 4 4 5% 7% 26%	2663
	21st to end	Night	15% 14% 5% 11% 7% 5% 4 4 6% 6% 23%	2163
March	1st to 10th	Night	15% 9% 4 9% 6% 5% 5% 4 6% 6% 31%	5018
	11th to 20th	Night	12% 11% 3 7% 5% 4 5% 4 5% 8% 38%	5089
	21st to end	Night	16% 9% 3 8% 4 4 4 3 5% 6% 37%	5588
April	1st to 10th	Night	17% 11% 4 9% 6% 5% 3 4 5% 6% 31%	2146
	11th to 20th	Night	17% 9% 3 6% 5% 5% 5% 4 5% 6% 36%	2028
	21st to end	Night	15% 9% 3 7% 4 5% 5% 4 6% 7% 36%	1890
May	1st to 10th	Night	20% 11% 4 9% 5% 4 3 3 4 5% 32%	4062
	11th to 20th	Night	12% 8% 3 9% 6% 5% 5% 4 6% 7% 34%	3674
	21st to end	Night	16% 7% 2 6% 4 4 4 4 5% 7% 42%	3926
June	1st to 10th	Night	10% 6% 3 7% 5% 5% 6% 4 7% 8% 38%	1600
	11th to 20th	Night	8% 6% 2 7% 6% 6% 4 4 6% 8% 43%	1600
	21st to end	Night	11% 6% 2 6% 3 5% 4 4 6% 9% 44%	1600
July	1st to 10th	Night	6% 6% 2 7% 5% 5% 5% 4 6% 9% 47%	3600
	11th to 20th	Night	8% 5% 2 7% 5% 4 5% 4 7% 9% 46%	3636
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 8% 50%	4428
August	1st to 10th	Night	10% 5% 2 6% 4 4 5% 4 7% 8% 44%	2915
	11th to 20th	Night	11% 7% 2 7% 5% 4 4 4 6% 8% 43%	2875
	21st to end	Night	7% 5% 2 5% 4 4 5% 4 7% 10% 48%	3383
September	1st to 10th	Night	12% 5% 2 6% 4 4 5% 4 5% 7% 47%	2000
	11th to 20th	Night	10% 5% 2 5% 3 3 4 3 4 8% 53%	2120
	21st to end	Night	15% 7% 3 8% 6% 4 4 4 5% 7% 38%	2238
October	1st to 10th	Night	16% 7% 3 7% 4 4 4 3 5% 6% 42%	2400
	11th to 20th	Night	19% 10% 3 8% 4 4 4 3 5% 7% 33%	2400
	21st to end	Night	22% 9% 3 6% 5% 4 5% 4 6% 6% 30%	2640
November	1st to 10th	Night	15% 9% 3 7% 5% 4 4 4 5% 6% 39%	2692
	11th to 20th	Night	14% 10% 4 8% 5% 5% 6% 4 6% 7% 30%	2940
	21st to end	Night	18% 12% 4 8% 6% 5% 5% 3 6% 6% 26%	2940
December	1st to 10th	Night	14% 15% 5% 11% 6% 6% 6% 4 6% 8% 19%	4720
	11th to 20th	Night	15% 17% 5% 10% 5% 5% 5% 4 5% 5% 25%	5348
	21st to end	Night	24% 16% 6% 12% 6% 6% 4 3 5% 5% 14%	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	59% 8% 12% 11% 8% 1	4662
	11th to 20th	Day	73% 8% 8% 6% 5% 1	5238
	21st to end	Day	69% 7% 9% 9% 5%	5780
February	1st to 10th	Day	67% 6% 9% 13% 4 1	1890
	11th to 20th	Day	63% 7% 11% 15% 4	1852
	21st to end	Day	61% 7% 12% 13% 6% 1	1636
March	1st to 10th	Day	54% 6% 15% 16% 9%	5045
	11th to 20th	Day	51% 6% 18% 16% 7% 2	5090
	21st to end	Day	52% 6% 9% 22% 10% 1	5586
April	1st to 10th	Day	54% 5% 12% 18% 11% 1	2473
	11th to 20th	Day	49% 6% 11% 19% 13% 2	2559
	21st to end	Day	49% 6% 12% 18% 12% 2	2730
May	1st to 10th	Day	51% 5% 12% 16% 10% 5%	5910
	11th to 20th	Day	50% 8% 11% 18% 12% 1	6220
	21st to end	Day	43% 7% 12% 21% 15% 2	6949
June	1st to 10th	Day	40% 8% 12% 22% 15% 2	2800
	11th to 20th	Day	39% 6% 15% 24% 14% 1	2800
	21st to end	Day	36% 8% 16% 25% 15% 1	2800
July	1st to 10th	Day	35% 6% 14% 27% 17% 2	6290
	11th to 20th	Day	35% 6% 15% 28% 15% 1	6245
	21st to end	Day	33% 6% 15% 27% 19% 1	6240
August	1st to 10th	Day	43% 6% 15% 22% 13% 1	4221
	11th to 20th	Day	42% 7% 17% 24% 10% 1	4213
	21st to end	Day	34% 6% 13% 34% 13% 1	4482
September	1st to 10th	Day	38% 7% 16% 25% 12% 1	2400
	11th to 20th	Day	33% 6% 14% 31% 15%	2275
	21st to end	Day	45% 7% 15% 23% 9% 1	2161
October	1st to 10th	Day	36% 6% 16% 26% 16% 1	3260
	11th to 20th	Day	43% 5% 13% 24% 15%	3240
	21st to end	Day	51% 4 16% 21% 8%	3538
November	1st to 10th	Day	49% 7% 14% 21% 8% 1	1822
	11th to 20th	Day	52% 8% 15% 15% 10% 1	1680
	21st to end	Day	58% 8% 16% 14% 4	1680
December	1st to 10th	Day	67% 5% 16% 9% 2	2680
	11th to 20th	Day	62% 6% 11% 11% 8% 1	3066
	21st to end	Day	74% 8% 8% 7% 3	4048
January	1st to 10th	Night	59% 7% 12% 16% 5%	8234
	11th to 20th	Night	62% 9% 9% 12% 8% 1	7705
	21st to end	Night	62% 7% 8% 13% 9%	8401
February	1st to 10th	Night	61% 7% 11% 15% 5%	2730
	11th to 20th	Night	57% 7% 13% 17% 6%	2665
	21st to end	Night	60% 8% 12% 13% 7%	2163
March	1st to 10th	Night	52% 6% 12% 18% 11% 2	5028
	11th to 20th	Night	44% 5% 19% 20% 11% 2	5090
	21st to end	Night	47% 4 11% 20% 16% 2	5588
April	1st to 10th	Night	54% 5% 10% 19% 11% 2	2146
	11th to 20th	Night	49% 5% 10% 19% 14% 2	2028
	21st to end	Night	47% 6% 11% 19% 15% 2	1890
May	1st to 10th	Night	54% 5% 9% 14% 12% 6%	4069
	11th to 20th	Night	45% 9% 13% 20% 11% 1	3675
	21st to end	Night	41% 6% 12% 23% 16% 1	3927
June	1st to 10th	Night	40% 9% 11% 22% 16% 2	1600
	11th to 20th	Night	38% 6% 13% 24% 17% 2	1600
	21st to end	Night	37% 6% 14% 24% 17% 2	1600
July	1st to 10th	Night	34% 4 14% 23% 22% 2	3560
	11th to 20th	Night	34% 5% 14% 29% 17% 2	3588
	21st to end	Night	32% 5% 14% 23% 24% 2	4297
August	1st to 10th	Night	36% 6% 14% 26% 15% 3	2904
	11th to 20th	Night	38% 7% 16% 28% 11%	2902
	21st to end	Night	31% 5% 15% 34% 14% 1	3383
September	1st to 10th	Night	36% 6% 14% 27% 15% 2	2000
	11th to 20th	Night	29% 6% 13% 33% 18% 1	2120
	21st to end	Night	45% 7% 11% 23% 13% 1	2238
October	1st to 10th	Night	35% 5% 8% 27% 23% 1	3920
	11th to 20th	Night	47% 4 13% 23% 13%	3899
	21st to end	Night	40% 5% 17% 27% 11% 1	4252
November	1st to 10th	Night	44% 7% 12% 24% 11% 1	2692
	11th to 20th	Night	51% 7% 14% 18% 9% 1	2940
	21st to end	Night	57% 9% 15% 16% 4	2940
December	1st to 10th	Night	62% 7% 17% 11% 3	4720
	11th to 20th	Night	60% 6% 10% 13% 10% 1	5348
	21st to end	Night	71% 7% 10% 9% 3	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	20% 22% 36% 15% 7%	220
	11th to 20th	Day	27% 21% 34% 13% 4 1	322
	21st to end	Day	24% 20% 33% 19% 4 1	363
February	1st to 10th	Day	24% 19% 38% 15% 3	330
	11th to 20th	Day	27% 21% 35% 15% 2	330
	21st to end	Day	28% 22% 33% 15% 1	300
March	1st to 10th	Day	23% 15% 34% 21% 6% 1	540
	11th to 20th	Day	24% 18% 31% 21% 5% 1	540
	21st to end	Day	27% 15% 29% 21% 7% 1	594
April	1st to 10th	Day	22% 15% 32% 23% 7% 1	540
	11th to 20th	Day	24% 17% 24% 22% 9% 3	532
	21st to end	Day	25% 8% 33% 23% 9% 2	540
May	1st to 10th	Day	22% 9% 28% 26% 12% 4	507
	11th to 20th	Day	17% 10% 21% 27% 20% 6%	527
	21st to end	Day	14% 7% 23% 29% 20% 8%	573
June	1st to 10th	Day	14% 10% 27% 33% 14% 3	530
	11th to 20th	Day	13% 7% 26% 29% 20% 4	530
	21st to end	Day	14% 6% 26% 30% 19% 5%	530
July	1st to 10th	Day	10% 3 17% 31% 29% 10%	525
	11th to 20th	Day	15% 5% 20% 29% 22% 9%	524
	21st to end	Day	9% 4 23% 35% 21% 9%	576
August	1st to 10th	Day	11% 3 17% 33% 24% 13%	526
	11th to 20th	Day	11% 6% 20% 28% 24% 12%	519
	21st to end	Day	13% 5% 20% 29% 21% 11%	583
September	1st to 10th	Day	14% 7% 21% 24% 22% 12%	530
	11th to 20th	Day	9% 6% 17% 23% 28% 17%	530
	21st to end	Day	16% 10% 26% 25% 15% 9%	530
October	1st to 10th	Day	19% 9% 25% 21% 17% 8%	530
	11th to 20th	Day	20% 16% 31% 21% 9% 3	530
	21st to end	Day	30% 15% 26% 20% 9%	583
November	1st to 10th	Day	21% 20% 32% 18% 7% 3	346
	11th to 20th	Day	20% 24% 30% 17% 6% 2	220
	21st to end	Day	28% 17% 35% 17% 3	220
December	1st to 10th	Day	27% 18% 36% 14% 4 1	220
	11th to 20th	Day	26% 26% 34% 12% 2	220
	21st to end	Day	25% 17% 37% 17% 5%	242
January	1st to 10th	Night	25% 17% 34% 17% 6%	840
	11th to 20th	Night	27% 19% 33% 18% 4	840
	21st to end	Night	19% 15% 38% 22% 5%	924
February	1st to 10th	Night	25% 17% 35% 20% 3	840
	11th to 20th	Night	21% 17% 34% 25% 3	823
	21st to end	Night	23% 15% 37% 22% 3	692
March	1st to 10th	Night	20% 14% 33% 26% 7%	840
	11th to 20th	Night	25% 14% 31% 22% 7%	840
	21st to end	Night	21% 10% 31% 28% 9% 1	924
April	1st to 10th	Night	23% 12% 31% 29% 5%	840
	11th to 20th	Night	22% 10% 30% 26% 10% 2	784
	21st to end	Night	19% 7% 30% 34% 11%	630
May	1st to 10th	Night	20% 5% 23% 32% 18% 2	603
	11th to 20th	Night	14% 6% 24% 39% 17% 1	441
	21st to end	Night	14% 4 23% 33% 23% 3	433
June	1st to 10th	Night	14% 3 31% 34% 17% 1	400
	11th to 20th	Night	13% 4 25% 37% 21%	400
	21st to end	Night	12% 5% 21% 45% 17% 1	400
July	1st to 10th	Night	6% 3 17% 48% 23% 2	390
	11th to 20th	Night	10% 4 21% 41% 22% 3	398
	21st to end	Night	9% 4 15% 44% 25% 3	657
August	1st to 10th	Night	9% 2 14% 39% 32% 4	597
	11th to 20th	Night	10% 3 16% 31% 35% 5%	594
	21st to end	Night	11% 2 18% 37% 28% 4	755
September	1st to 10th	Night	14% 6% 17% 35% 24% 6%	800
	11th to 20th	Night	11% 5% 15% 30% 33% 7%	800
	21st to end	Night	17% 6% 22% 28% 22% 5%	800
October	1st to 10th	Night	18% 7% 24% 28% 20% 3	800
	11th to 20th	Night	24% 11% 29% 26% 9% 2	800
	21st to end	Night	27% 11% 28% 27% 7%	880
November	1st to 10th	Night	21% 12% 29% 27% 10% 1	820
	11th to 20th	Night	22% 15% 32% 21% 8% 2	840
	21st to end	Night	25% 13% 35% 20% 6%	840
December	1st to 10th	Night	27% 18% 31% 18% 6%	840
	11th to 20th	Night	24% 19% 34% 18% 5%	840
	21st to end	Night	28% 15% 32% 21% 3	924

Page generated at 2026-04-29 02:21:41. Version ac07

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