Morris
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Morris 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	11% 9% 3 9% 5% 5% 5% 4 6% 8% 35%	137987
	Night	9% 10% 4 10% 6% 5% 5% 4 6% 7% 33%	134361
Transparency	Day	46% 4 16% 25% 9% 1	141415
	Night	49% 4 14% 23% 10% 1	139022
Seeing	Day	15% 8% 30% 29% 14% 4	18449
	Night	15% 6% 31% 34% 13% 1	28415

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	6% 14% 6% 13% 8% 6% 5% 6% 6% 9% 20%	4124
	11th to 20th	Day	4 9% 4 15% 10% 8% 10% 9% 8% 8% 13%	4213
	21st to end	Day	5% 11% 5% 13% 7% 7% 7% 6% 7% 9% 23%	5188
February	1st to 10th	Day	9% 11% 6% 13% 9% 6% 8% 5% 7% 5% 20%	1808
	11th to 20th	Day	7% 10% 4 11% 7% 8% 8% 5% 8% 8% 25%	1844
	21st to end	Day	7% 8% 4 14% 10% 7% 7% 6% 6% 8% 24%	1661
March	1st to 10th	Day	10% 10% 3 8% 8% 5% 5% 4 6% 9% 31%	4701
	11th to 20th	Day	8% 11% 5% 13% 8% 6% 5% 5% 7% 8% 23%	5090
	21st to end	Day	10% 13% 6% 13% 6% 5% 5% 4 5% 6% 28%	5585
April	1st to 10th	Day	10% 13% 4 9% 5% 5% 5% 4 5% 7% 34%	2551
	11th to 20th	Day	13% 11% 4 8% 6% 4 4 4 6% 7% 32%	2702
	21st to end	Day	18% 8% 4 8% 5% 4 4 3 6% 6% 34%	2730
May	1st to 10th	Day	10% 8% 3 6% 4 4 4 3 5% 7% 46%	7798
	11th to 20th	Day	17% 9% 3 7% 5% 5% 5% 4 6% 7% 34%	8577
	21st to end	Day	12% 7% 2 6% 4 4 4 4 5% 7% 46%	9683
June	1st to 10th	Day	13% 7% 3 6% 5% 5% 5% 4 7% 9% 37%	3150
	11th to 20th	Day	14% 6% 2 7% 5% 5% 5% 4 7% 8% 38%	3076
	21st to end	Day	11% 6% 2 6% 5% 6% 6% 5% 8% 9% 36%	3000
July	1st to 10th	Day	8% 4 2 5% 4 4 5% 4 8% 10% 46%	6799
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 6% 8% 45%	6800
	21st to end	Day	7% 5% 2 6% 4 5% 5% 5% 7% 9% 45%	7234
August	1st to 10th	Day	8% 5% 2 6% 4 5% 5% 4 6% 8% 46%	4378
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 6% 9% 46%	4171
	21st to end	Day	11% 5% 2 5% 4 3 4 3 6% 9% 48%	4675
September	1st to 10th	Day	10% 6% 2 5% 4 3 4 3 6% 7% 50%	2468
	11th to 20th	Day	14% 7% 2 7% 5% 4 4 4 6% 8% 40%	2200
	21st to end	Day	15% 7% 2 5% 3 3 4 4 6% 8% 43%	2200
October	1st to 10th	Day	17% 9% 2 6% 4 4 4 4 5% 6% 39%	2050
	11th to 20th	Day	15% 10% 3 8% 5% 4 4 3 5% 7% 35%	1960
	21st to end	Day	16% 12% 4 9% 6% 5% 5% 4 5% 7% 29%	1980
November	1st to 10th	Day	15% 15% 4 9% 5% 4 3 4 5% 6% 30%	1701
	11th to 20th	Day	11% 14% 6% 14% 6% 4 4 3 6% 5% 28%	1680
	21st to end	Day	12% 15% 5% 11% 8% 5% 5% 4 4 5% 26%	1566
December	1st to 10th	Day	10% 15% 5% 15% 9% 9% 6% 4 5% 6% 16%	2360
	11th to 20th	Day	9% 14% 5% 12% 6% 6% 5% 5% 7% 7% 22%	2709
	21st to end	Day	9% 14% 6% 18% 8% 7% 5% 4 6% 5% 19%	3575
January	1st to 10th	Night	5% 13% 6% 16% 7% 8% 6% 5% 6% 8% 19%	8800
	11th to 20th	Night	4 13% 6% 13% 9% 9% 10% 6% 7% 6% 17%	8701
	21st to end	Night	6% 13% 6% 12% 6% 6% 7% 5% 8% 8% 25%	9026
February	1st to 10th	Night	8% 12% 5% 11% 6% 8% 7% 5% 6% 6% 25%	2811
	11th to 20th	Night	7% 10% 3 9% 6% 6% 6% 5% 7% 7% 34%	2663
	21st to end	Night	6% 11% 5% 13% 6% 6% 5% 5% 6% 6% 30%	2165
March	1st to 10th	Night	8% 11% 3 10% 6% 5% 5% 5% 7% 9% 32%	5373
	11th to 20th	Night	7% 10% 3 9% 6% 5% 6% 4 6% 7% 37%	5089
	21st to end	Night	11% 14% 4 12% 6% 5% 4 3 5% 5% 32%	5588
April	1st to 10th	Night	10% 9% 3 7% 5% 4 5% 4 7% 7% 40%	2067
	11th to 20th	Night	13% 11% 4 7% 6% 5% 4 4 4 6% 35%	1869
	21st to end	Night	13% 8% 3 7% 5% 5% 5% 4 5% 6% 37%	1890
May	1st to 10th	Night	11% 6% 2 6% 4 5% 5% 4 6% 8% 44%	5114
	11th to 20th	Night	16% 7% 3 6% 4 4 4 4 6% 7% 40%	4299
	21st to end	Night	12% 6% 2 5% 4 3 4 3 5% 7% 49%	4526
June	1st to 10th	Night	11% 6% 2 5% 5% 3 5% 4 6% 9% 45%	1470
	11th to 20th	Night	12% 5% 2 6% 6% 4 3 4 6% 9% 43%	1435
	21st to end	Night	10% 5% 2 4 5% 4 5% 5% 7% 10% 43%	1400
July	1st to 10th	Night	7% 3 2 5% 3 4 5% 4 6% 10% 51%	3180
	11th to 20th	Night	6% 3 1 5% 4 4 4 4 6% 9% 53%	3180
	21st to end	Night	5% 4 2 5% 4 5% 5% 5% 7% 11% 48%	3639
August	1st to 10th	Night	5% 4 2 6% 4 5% 4 5% 6% 9% 50%	2780
	11th to 20th	Night	10% 4 2 5% 4 3 3 4 6% 10% 49%	2888
	21st to end	Night	9% 5% 2 5% 4 3 4 4 5% 8% 50%	3234
September	1st to 10th	Night	8% 4 2 5% 3 3 4 4 6% 8% 54%	1930
	11th to 20th	Night	13% 6% 2 5% 3 3 4 3 6% 8% 47%	2200
	21st to end	Night	14% 6% 2 5% 4 3 4 3 5% 7% 45%	2200
October	1st to 10th	Night	17% 7% 3 7% 4 4 4 3 5% 6% 39%	2330
	11th to 20th	Night	15% 11% 3 7% 4 3 4 3 5% 7% 38%	2435
	21st to end	Night	14% 10% 3 8% 5% 5% 4 3 5% 8% 34%	2860
November	1st to 10th	Night	12% 14% 4 9% 5% 5% 5% 4 6% 6% 31%	2816
	11th to 20th	Night	12% 14% 6% 12% 6% 4 4 3 5% 6% 28%	2940
	21st to end	Night	11% 14% 5% 13% 8% 5% 4 3 4 6% 27%	3050
December	1st to 10th	Night	7% 15% 6% 17% 12% 7% 6% 4 5% 5% 16%	5050
	11th to 20th	Night	7% 15% 6% 15% 8% 5% 5% 4 7% 6% 22%	5718
	21st to end	Night	8% 12% 5% 18% 9% 8% 5% 3 6% 5% 21%	7645

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	60% 3 11% 20% 6%	4125
	11th to 20th	Day	65% 5% 10% 15% 6%	4241
	21st to end	Day	57% 4 11% 22% 6%	5188
February	1st to 10th	Day	63% 4 11% 13% 8% 1	1808
	11th to 20th	Day	55% 4 14% 19% 8%	1853
	21st to end	Day	57% 3 14% 17% 8%	1661
March	1st to 10th	Day	49% 4 20% 17% 10%	4703
	11th to 20th	Day	56% 6% 16% 16% 6%	5090
	21st to end	Day	56% 4 13% 20% 7%	5585
April	1st to 10th	Day	49% 4 11% 25% 10% 1	2551
	11th to 20th	Day	51% 3 13% 21% 11% 1	2702
	21st to end	Day	51% 3 15% 22% 8% 2	2730
May	1st to 10th	Day	37% 4 11% 30% 17% 1	7809
	11th to 20th	Day	48% 4 11% 24% 12% 2	8581
	21st to end	Day	37% 3 10% 26% 20% 3	9683
June	1st to 10th	Day	42% 6% 17% 26% 9% 1	3150
	11th to 20th	Day	43% 5% 16% 25% 10% 1	3076
	21st to end	Day	42% 6% 21% 25% 7%	3000
July	1st to 10th	Day	32% 5% 28% 29% 6%	6726
	11th to 20th	Day	36% 4 21% 33% 6%	6719
	21st to end	Day	35% 5% 24% 29% 8%	7024
August	1st to 10th	Day	35% 4 19% 30% 11%	4362
	11th to 20th	Day	35% 4 20% 35% 6%	4210
	21st to end	Day	34% 3 24% 31% 8%	4674
September	1st to 10th	Day	33% 3 19% 34% 11% 1	2468
	11th to 20th	Day	42% 4 20% 26% 6% 1	2200
	21st to end	Day	39% 4 17% 33% 8%	2200
October	1st to 10th	Day	38% 3 14% 32% 13%	3336
	11th to 20th	Day	41% 4 11% 30% 14%	3178
	21st to end	Day	49% 3 14% 25% 8%	3190
November	1st to 10th	Day	55% 4 15% 20% 5% 1	1701
	11th to 20th	Day	59% 4 15% 17% 5% 1	1680
	21st to end	Day	63% 4 14% 15% 3	1566
December	1st to 10th	Day	70% 5% 12% 10% 3	2360
	11th to 20th	Day	60% 3 15% 14% 8%	2710
	21st to end	Day	68% 4 7% 17% 5%	3575
January	1st to 10th	Night	63% 3 13% 15% 6%	8800
	11th to 20th	Night	66% 5% 8% 17% 5%	8748
	21st to end	Night	55% 4 12% 22% 6%	9026
February	1st to 10th	Night	59% 4 12% 16% 9%	2811
	11th to 20th	Night	47% 4 16% 23% 10%	2664
	21st to end	Night	53% 5% 12% 20% 10%	2165
March	1st to 10th	Night	47% 6% 17% 18% 10% 3	5384
	11th to 20th	Night	45% 4 15% 23% 12% 1	5090
	21st to end	Night	55% 2 10% 22% 9% 1	5588
April	1st to 10th	Night	42% 3 12% 26% 15% 3	2067
	11th to 20th	Night	50% 3 9% 23% 13% 2	1869
	21st to end	Night	47% 3 11% 26% 11% 2	1890
May	1st to 10th	Night	38% 4 10% 31% 16%	5124
	11th to 20th	Night	43% 4 11% 24% 16% 2	4300
	21st to end	Night	35% 3 9% 25% 24% 3	4526
June	1st to 10th	Night	35% 4 18% 27% 14% 2	1470
	11th to 20th	Night	37% 5% 17% 27% 12% 2	1435
	21st to end	Night	35% 6% 21% 30% 8% 1	1400
July	1st to 10th	Night	28% 6% 26% 31% 8% 1	3145
	11th to 20th	Night	27% 4 21% 40% 8%	3138
	21st to end	Night	30% 5% 27% 30% 8% 1	3535
August	1st to 10th	Night	31% 5% 17% 32% 14% 1	2772
	11th to 20th	Night	31% 4 25% 30% 9%	2915
	21st to end	Night	33% 4 19% 34% 10% 1	3234
September	1st to 10th	Night	28% 4 16% 36% 15% 1	1930
	11th to 20th	Night	36% 4 20% 28% 10% 1	2200
	21st to end	Night	39% 3 14% 31% 12% 1	2200
October	1st to 10th	Night	38% 2 12% 33% 13% 1	3811
	11th to 20th	Night	40% 3 11% 31% 14%	3958
	21st to end	Night	44% 3 14% 31% 8%	4610
November	1st to 10th	Night	54% 4 14% 19% 7% 2	2816
	11th to 20th	Night	58% 4 15% 15% 6% 1	2940
	21st to end	Night	60% 4 15% 15% 6%	3050
December	1st to 10th	Night	70% 4 12% 11% 3	5050
	11th to 20th	Night	62% 4 12% 13% 9%	5716
	21st to end	Night	65% 3 10% 17% 5%	7645

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	10% 7% 33% 32% 16% 2	330
	11th to 20th	Day	12% 7% 32% 33% 14% 2	330
	21st to end	Day	14% 6% 33% 31% 13% 3	363
February	1st to 10th	Day	15% 11% 34% 30% 9% 1	330
	11th to 20th	Day	11% 11% 32% 34% 11% 2	330
	21st to end	Day	10% 6% 42% 29% 12% 1	273
March	1st to 10th	Day	14% 6% 38% 29% 11% 3	330
	11th to 20th	Day	14% 12% 33% 25% 13% 3	330
	21st to end	Day	15% 9% 33% 31% 10% 3	363
April	1st to 10th	Day	15% 13% 29% 32% 9% 2	571
	11th to 20th	Day	21% 10% 31% 25% 11% 2	740
	21st to end	Day	20% 10% 29% 27% 12% 2	750
May	1st to 10th	Day	16% 11% 30% 27% 13% 3	753
	11th to 20th	Day	21% 9% 31% 25% 11% 4	775
	21st to end	Day	17% 7% 26% 29% 15% 6%	844
June	1st to 10th	Day	15% 8% 30% 26% 14% 7%	780
	11th to 20th	Day	16% 8% 31% 30% 11% 3	756
	21st to end	Day	13% 6% 27% 32% 17% 5%	730
July	1st to 10th	Day	9% 3 26% 30% 20% 10%	721
	11th to 20th	Day	13% 6% 26% 29% 20% 6%	718
	21st to end	Day	6% 5% 26% 34% 21% 9%	794
August	1st to 10th	Day	9% 4 24% 33% 22% 8%	726
	11th to 20th	Day	12% 4 21% 33% 20% 10%	715
	21st to end	Day	13% 6% 26% 29% 20% 5%	803
September	1st to 10th	Day	11% 7% 35% 29% 15% 3	598
	11th to 20th	Day	18% 8% 35% 25% 11% 2	330
	21st to end	Day	22% 7% 33% 24% 14% 1	330
October	1st to 10th	Day	22% 9% 27% 28% 13% 2	330
	11th to 20th	Day	16% 10% 37% 27% 9% 1	330
	21st to end	Day	26% 10% 28% 24% 11% 1	363
November	1st to 10th	Day	26% 9% 27% 26% 11% 1	330
	11th to 20th	Day	20% 10% 35% 25% 8% 2	330
	21st to end	Day	16% 12% 36% 27% 8%	330
December	1st to 10th	Day	17% 6% 36% 29% 10% 2	330
	11th to 20th	Day	17% 12% 35% 29% 7%	330
	21st to end	Day	18% 7% 28% 31% 12% 4	363
January	1st to 10th	Night	12% 7% 33% 31% 14% 3	1050
	11th to 20th	Night	16% 7% 33% 32% 12%	1050
	21st to end	Night	14% 8% 35% 32% 11% 1	1155
February	1st to 10th	Night	15% 6% 30% 34% 12% 2	1050
	11th to 20th	Night	12% 6% 29% 37% 14% 3	1029
	21st to end	Night	11% 8% 33% 34% 13% 2	781
March	1st to 10th	Night	16% 7% 31% 32% 12% 2	795
	11th to 20th	Night	9% 7% 39% 31% 12% 1	630
	21st to end	Night	20% 5% 28% 30% 14% 3	693
April	1st to 10th	Night	15% 8% 31% 34% 11% 1	630
	11th to 20th	Night	19% 6% 30% 34% 10%	623
	21st to end	Night	17% 7% 29% 35% 12% 1	630
May	1st to 10th	Night	16% 7% 34% 32% 11%	630
	11th to 20th	Night	18% 7% 29% 33% 13%	621
	21st to end	Night	19% 4 31% 35% 11% 1	683
June	1st to 10th	Night	14% 5% 31% 35% 15% 1	630
	11th to 20th	Night	15% 5% 31% 35% 13% 1	615
	21st to end	Night	12% 5% 24% 40% 20% 1	600
July	1st to 10th	Night	8% 2 23% 44% 22% 1	585
	11th to 20th	Night	6% 4 27% 43% 19% 1	582
	21st to end	Night	7% 2 23% 45% 20% 3	657
August	1st to 10th	Night	10% 2 21% 46% 20% 1	597
	11th to 20th	Night	10% 3 20% 40% 23% 3	594
	21st to end	Night	11% 4 27% 38% 20% 1	660
September	1st to 10th	Night	9% 2 32% 39% 16% 2	600
	11th to 20th	Night	15% 4 29% 39% 12% 1	600
	21st to end	Night	18% 5% 30% 34% 13% 1	600
October	1st to 10th	Night	22% 7% 34% 28% 9% 1	730
	11th to 20th	Night	23% 6% 31% 29% 10%	835
	21st to end	Night	19% 8% 31% 33% 9% 1	1100
November	1st to 10th	Night	19% 10% 32% 28% 10% 1	1025
	11th to 20th	Night	19% 8% 34% 28% 9% 2	1050
	21st to end	Night	18% 9% 40% 26% 7% 1	1050
December	1st to 10th	Night	14% 8% 31% 33% 13% 2	1050
	11th to 20th	Night	18% 7% 34% 32% 8% 2	1050
	21st to end	Night	20% 6% 33% 28% 12% 1	1155

Page generated at 2026-06-13 01:31:41. Version ac07

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