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 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	11% 9% 3 9% 6% 5% 5% 4 6% 8% 34%	108327
	Night	9% 10% 4 10% 6% 5% 5% 4 6% 7% 33%	110471
Transparency	Day	47% 4 16% 24% 8%	111804
	Night	50% 4 14% 23% 9% 1	115155
Seeing	Day	15% 7% 29% 29% 15% 4	16553
	Night	15% 6% 30% 34% 13% 1	26671

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	5% 15% 6% 13% 7% 7% 5% 6% 7% 10% 19%	3178
	11th to 20th	Day	5% 10% 4 15% 10% 9% 9% 10% 8% 8% 12%	3225
	21st to end	Day	7% 14% 7% 16% 8% 5% 7% 4 6% 7% 19%	4004
February	1st to 10th	Day	9% 11% 6% 13% 9% 6% 8% 5% 7% 5% 21%	1722
	11th to 20th	Day	7% 9% 4 11% 7% 8% 8% 5% 8% 8% 25%	1754
	21st to end	Day	7% 9% 4 13% 10% 7% 7% 5% 6% 8% 25%	1507
March	1st to 10th	Day	13% 10% 4 8% 9% 5% 5% 4 6% 8% 28%	3203
	11th to 20th	Day	7% 11% 6% 15% 9% 7% 5% 5% 7% 7% 22%	3480
	21st to end	Day	9% 13% 6% 13% 6% 5% 4 3 5% 6% 30%	3814
April	1st to 10th	Day	10% 12% 4 9% 5% 5% 5% 4 5% 7% 34%	2307
	11th to 20th	Day	13% 11% 4 8% 6% 4 5% 4 6% 7% 33%	2442
	21st to end	Day	18% 8% 4 8% 5% 4 4 3 6% 6% 34%	2470
May	1st to 10th	Day	18% 10% 3 7% 4 4 4 3 5% 7% 34%	4195
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 4 6% 7% 34%	4598
	21st to end	Day	19% 9% 3 7% 4 4 4 4 5% 6% 35%	5173
June	1st to 10th	Day	13% 7% 3 6% 5% 4 5% 4 7% 8% 37%	2850
	11th to 20th	Day	15% 6% 2 6% 5% 5% 5% 4 7% 7% 38%	2850
	21st to end	Day	11% 6% 2 6% 5% 6% 6% 5% 8% 9% 37%	2850
July	1st to 10th	Day	9% 3 1 5% 5% 4 5% 4 8% 11% 45%	4750
	11th to 20th	Day	8% 4 1 5% 4 4 5% 4 6% 9% 51%	4750
	21st to end	Day	5% 4 2 5% 4 4 4 5% 8% 9% 51%	5035
August	1st to 10th	Day	8% 5% 2 6% 4 5% 5% 4 6% 8% 46%	4243
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 6% 9% 46%	4041
	21st to end	Day	12% 5% 2 5% 4 3 4 3 6% 9% 48%	4532
September	1st to 10th	Day	9% 6% 2 5% 4 3 4 3 6% 7% 51%	2345
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 4 6% 8% 41%	2090
	21st to end	Day	16% 7% 2 6% 3 3 4 4 6% 8% 42%	2090
October	1st to 10th	Day	17% 10% 2 6% 4 4 4 3 5% 6% 38%	1948
	11th to 20th	Day	14% 10% 3 8% 5% 4 4 3 5% 7% 35%	1862
	21st to end	Day	16% 12% 4 9% 5% 5% 5% 4 5% 7% 29%	1881
November	1st to 10th	Day	15% 16% 4 8% 5% 4 3 4 5% 6% 30%	1619
	11th to 20th	Day	11% 14% 7% 14% 6% 4 4 3 6% 5% 26%	1600
	21st to end	Day	13% 15% 5% 11% 8% 5% 5% 4 4 5% 26%	1492
December	1st to 10th	Day	10% 15% 5% 15% 9% 9% 6% 4 5% 6% 15%	2290
	11th to 20th	Day	9% 14% 5% 12% 6% 6% 5% 5% 7% 8% 22%	2639
	21st to end	Day	8% 14% 6% 18% 8% 7% 5% 4 6% 5% 19%	3498
January	1st to 10th	Night	4 13% 6% 15% 8% 9% 7% 5% 6% 7% 20%	6787
	11th to 20th	Night	4 13% 6% 13% 9% 10% 9% 7% 7% 5% 17%	6679
	21st to end	Night	7% 17% 7% 14% 6% 5% 5% 4 6% 6% 21%	6974
February	1st to 10th	Night	9% 12% 5% 11% 6% 8% 7% 6% 6% 6% 25%	2677
	11th to 20th	Night	6% 9% 3 9% 6% 6% 7% 5% 7% 8% 34%	2533
	21st to end	Night	6% 11% 5% 14% 5% 5% 5% 5% 6% 6% 31%	1966
March	1st to 10th	Night	11% 12% 3 10% 7% 5% 5% 4 5% 8% 30%	3643
	11th to 20th	Night	6% 9% 3 9% 6% 5% 5% 4 6% 8% 39%	3479
	21st to end	Night	10% 14% 4 12% 5% 4 4 3 5% 5% 33%	3817
April	1st to 10th	Night	9% 8% 2 7% 5% 4 6% 4 7% 8% 40%	1871
	11th to 20th	Night	14% 11% 4 7% 6% 5% 4 4 5% 6% 35%	1689
	21st to end	Night	13% 9% 3 7% 5% 5% 5% 4 5% 7% 38%	1710
May	1st to 10th	Night	18% 9% 3 6% 4 5% 5% 4 6% 6% 35%	2754
	11th to 20th	Night	16% 7% 3 7% 4 4 3 4 5% 5% 41%	2304
	21st to end	Night	18% 8% 2 4 3 3 3 4 5% 6% 43%	2414
June	1st to 10th	Night	11% 6% 2 5% 5% 3 5% 4 6% 8% 45%	1330
	11th to 20th	Night	13% 5% 2 6% 6% 4 3 4 6% 9% 44%	1330
	21st to end	Night	10% 4 2 4 5% 4 5% 5% 6% 10% 44%	1330
July	1st to 10th	Night	8% 2 1 4 3 4 4 4 6% 10% 54%	2220
	11th to 20th	Night	5% 3 1 4 3 4 4 4 6% 9% 58%	2220
	21st to end	Night	6% 3 1 4 3 4 5% 5% 8% 10% 50%	2528
August	1st to 10th	Night	5% 4 2 6% 4 5% 4 4 6% 9% 50%	2695
	11th to 20th	Night	10% 4 2 5% 4 4 3 4 5% 10% 48%	2798
	21st to end	Night	9% 5% 2 5% 4 4 4 4 5% 8% 50%	3135
September	1st to 10th	Night	9% 3 2 5% 3 3 3 4 6% 8% 55%	1833
	11th to 20th	Night	12% 6% 2 5% 3 3 4 3 6% 8% 48%	2090
	21st to end	Night	15% 6% 2 5% 4 4 4 3 5% 7% 43%	2090
October	1st to 10th	Night	17% 8% 3 7% 4 4 4 3 5% 6% 38%	2213
	11th to 20th	Night	15% 10% 3 7% 4 3 4 3 5% 7% 38%	2313
	21st to end	Night	13% 11% 3 8% 5% 5% 4 3 5% 8% 34%	2717
November	1st to 10th	Night	12% 15% 4 9% 5% 5% 5% 4 5% 6% 31%	2679
	11th to 20th	Night	12% 14% 6% 12% 6% 4 4 3 5% 6% 27%	2800
	21st to end	Night	12% 14% 5% 13% 8% 5% 4 3 4 6% 27%	2905
December	1st to 10th	Night	7% 15% 6% 17% 13% 7% 6% 4 5% 5% 16%	4900
	11th to 20th	Night	7% 15% 6% 15% 8% 5% 5% 4 7% 6% 22%	5568
	21st to end	Night	8% 12% 5% 18% 9% 8% 5% 3 6% 5% 21%	7480

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% 3 12% 20% 6%	3179
	11th to 20th	Day	66% 5% 9% 15% 6%	3253
	21st to end	Day	64% 4 13% 15% 3	4004
February	1st to 10th	Day	62% 5% 11% 14% 8% 1	1722
	11th to 20th	Day	54% 4 14% 19% 9%	1763
	21st to end	Day	56% 3 15% 18% 9%	1507
March	1st to 10th	Day	55% 5% 17% 20% 5%	3205
	11th to 20th	Day	58% 7% 14% 16% 5%	3480
	21st to end	Day	54% 4 13% 21% 8%	3814
April	1st to 10th	Day	49% 4 10% 26% 10% 1	2307
	11th to 20th	Day	50% 3 12% 22% 11% 1	2442
	21st to end	Day	51% 3 15% 22% 7% 2	2470
May	1st to 10th	Day	49% 5% 12% 21% 11% 1	4206
	11th to 20th	Day	48% 4 13% 23% 11% 1	4602
	21st to end	Day	50% 4 12% 25% 9% 1	5173
June	1st to 10th	Day	42% 5% 18% 25% 10% 1	2850
	11th to 20th	Day	43% 5% 16% 25% 11% 1	2850
	21st to end	Day	41% 6% 21% 25% 7%	2850
July	1st to 10th	Day	31% 6% 27% 29% 6%	4676
	11th to 20th	Day	29% 4 23% 35% 8%	4669
	21st to end	Day	29% 5% 23% 35% 8%	4875
August	1st to 10th	Day	35% 4 19% 30% 11%	4227
	11th to 20th	Day	34% 5% 20% 35% 6%	4080
	21st to end	Day	34% 3 24% 31% 8%	4531
September	1st to 10th	Day	32% 3 18% 34% 11% 1	2345
	11th to 20th	Day	41% 4 20% 27% 7% 1	2090
	21st to end	Day	40% 4 16% 32% 8%	2090
October	1st to 10th	Day	38% 3 14% 31% 13%	3234
	11th to 20th	Day	41% 4 11% 30% 14%	3080
	21st to end	Day	49% 3 14% 26% 8%	3091
November	1st to 10th	Day	55% 5% 15% 20% 5% 1	1619
	11th to 20th	Day	60% 4 14% 17% 5%	1600
	21st to end	Day	63% 4 14% 15% 3	1492
December	1st to 10th	Day	70% 5% 12% 10% 3	2290
	11th to 20th	Day	60% 3 15% 14% 8%	2640
	21st to end	Day	68% 4 7% 17% 5%	3498
January	1st to 10th	Night	62% 3 12% 16% 7%	6787
	11th to 20th	Night	65% 5% 8% 17% 5%	6726
	21st to end	Night	63% 4 13% 16% 4	6974
February	1st to 10th	Night	58% 4 12% 16% 9%	2677
	11th to 20th	Night	46% 4 16% 23% 10%	2534
	21st to end	Night	52% 5% 12% 21% 10%	1966
March	1st to 10th	Night	50% 6% 13% 22% 8%	3654
	11th to 20th	Night	42% 5% 18% 24% 10% 1	3480
	21st to end	Night	53% 3 12% 22% 9% 1	3817
April	1st to 10th	Night	41% 3 12% 26% 15% 3	1871
	11th to 20th	Night	50% 3 9% 22% 14% 2	1689
	21st to end	Night	46% 3 12% 26% 11% 2	1710
May	1st to 10th	Night	47% 5% 11% 25% 12%	2763
	11th to 20th	Night	44% 3 12% 25% 11% 3	2305
	21st to end	Night	42% 4 12% 27% 14% 1	2414
June	1st to 10th	Night	36% 5% 18% 27% 13% 2	1330
	11th to 20th	Night	37% 5% 16% 27% 13% 2	1330
	21st to end	Night	34% 6% 21% 30% 8% 1	1330
July	1st to 10th	Night	25% 7% 26% 33% 8% 1	2185
	11th to 20th	Night	22% 4 21% 42% 11% 1	2178
	21st to end	Night	28% 4 24% 33% 10% 1	2448
August	1st to 10th	Night	30% 5% 16% 33% 14% 1	2687
	11th to 20th	Night	31% 4 24% 30% 10%	2825
	21st to end	Night	33% 4 19% 34% 10% 1	3135
September	1st to 10th	Night	28% 4 15% 36% 16% 1	1833
	11th to 20th	Night	35% 4 20% 30% 11% 1	2090
	21st to end	Night	40% 3 14% 30% 12% 1	2090
October	1st to 10th	Night	38% 2 12% 33% 13% 1	3694
	11th to 20th	Night	39% 3 11% 32% 14%	3836
	21st to end	Night	44% 3 14% 31% 8%	4467
November	1st to 10th	Night	54% 4 14% 19% 7% 1	2679
	11th to 20th	Night	59% 4 15% 16% 6% 1	2800
	21st to end	Night	60% 4 15% 15% 6%	2905
December	1st to 10th	Night	71% 4 12% 10% 3	4900
	11th to 20th	Night	62% 4 12% 13% 9%	5566
	21st to end	Night	65% 3 10% 17% 5%	7480

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	9% 6% 32% 32% 17% 3	300
	11th to 20th	Day	13% 7% 30% 34% 14% 2	300
	21st to end	Day	15% 6% 32% 32% 13% 3	330
February	1st to 10th	Day	15% 9% 34% 31% 10% 1	300
	11th to 20th	Day	10% 11% 33% 33% 10% 2	300
	21st to end	Day	9% 6% 42% 28% 13% 1	225
March	1st to 10th	Day	14% 5% 35% 31% 12% 3	270
	11th to 20th	Day	13% 11% 31% 28% 14% 4	270
	21st to end	Day	14% 6% 30% 34% 11% 3	297
April	1st to 10th	Day	14% 11% 29% 33% 11% 3	487
	11th to 20th	Day	21% 8% 31% 26% 12% 2	640
	21st to end	Day	20% 10% 30% 26% 12% 2	650
May	1st to 10th	Day	18% 11% 29% 26% 13% 3	653
	11th to 20th	Day	20% 8% 29% 27% 12% 5%	675
	21st to end	Day	19% 7% 25% 29% 15% 4	734
June	1st to 10th	Day	15% 8% 29% 26% 15% 8%	680
	11th to 20th	Day	17% 8% 31% 30% 11% 4	680
	21st to end	Day	13% 6% 25% 33% 18% 5%	680
July	1st to 10th	Day	10% 3 26% 29% 20% 11%	671
	11th to 20th	Day	12% 6% 25% 30% 21% 7%	668
	21st to end	Day	5% 5% 26% 33% 22% 9%	739
August	1st to 10th	Day	8% 4 24% 33% 22% 8%	676
	11th to 20th	Day	12% 3 20% 34% 20% 10%	665
	21st to end	Day	14% 6% 26% 28% 20% 5%	748
September	1st to 10th	Day	11% 7% 35% 29% 15% 3	555
	11th to 20th	Day	16% 9% 37% 25% 11% 2	300
	21st to end	Day	23% 7% 33% 24% 12% 1	300
October	1st to 10th	Day	23% 10% 26% 27% 13% 2	300
	11th to 20th	Day	14% 8% 38% 28% 10% 1	300
	21st to end	Day	26% 10% 30% 22% 11% 1	330
November	1st to 10th	Day	26% 6% 27% 28% 12% 1	300
	11th to 20th	Day	21% 10% 35% 24% 8% 2	300
	21st to end	Day	18% 11% 36% 26% 8%	300
December	1st to 10th	Day	16% 5% 37% 30% 10% 2	300
	11th to 20th	Day	16% 11% 34% 31% 8%	300
	21st to end	Day	17% 5% 29% 31% 13% 5%	330
January	1st to 10th	Night	12% 7% 33% 32% 14% 3	1000
	11th to 20th	Night	16% 7% 31% 33% 12%	1000
	21st to end	Night	14% 8% 34% 32% 11% 1	1100
February	1st to 10th	Night	15% 6% 30% 35% 13% 2	1000
	11th to 20th	Night	12% 6% 29% 38% 13% 3	979
	21st to end	Night	11% 7% 32% 34% 14% 2	710
March	1st to 10th	Night	16% 6% 30% 33% 13% 2	719
	11th to 20th	Night	10% 6% 38% 31% 14% 1	570
	21st to end	Night	19% 5% 26% 31% 15% 3	627
April	1st to 10th	Night	13% 8% 33% 34% 11% 1	570
	11th to 20th	Night	19% 6% 29% 34% 11% 1	563
	21st to end	Night	17% 7% 29% 35% 11% 1	570
May	1st to 10th	Night	17% 7% 32% 32% 11%	570
	11th to 20th	Night	17% 7% 28% 34% 14% 1	561
	21st to end	Night	20% 4 32% 34% 10% 1	617
June	1st to 10th	Night	14% 5% 29% 35% 16% 1	570
	11th to 20th	Night	16% 5% 31% 34% 14% 1	570
	21st to end	Night	12% 4 23% 40% 20% 1	570
July	1st to 10th	Night	8% 2 23% 44% 22% 1	555
	11th to 20th	Night	6% 4 26% 43% 19% 1	552
	21st to end	Night	8% 2 22% 45% 20% 3	624
August	1st to 10th	Night	10% 2 21% 46% 20% 1	567
	11th to 20th	Night	10% 3 20% 40% 24% 3	564
	21st to end	Night	11% 3 26% 37% 21% 1	627
September	1st to 10th	Night	10% 2 31% 38% 16% 2	570
	11th to 20th	Night	14% 4 28% 39% 13% 1	570
	21st to end	Night	18% 4 31% 34% 11% 1	570
October	1st to 10th	Night	22% 7% 33% 28% 9% 1	693
	11th to 20th	Night	22% 6% 31% 30% 10%	793
	21st to end	Night	19% 8% 31% 33% 9% 1	1045
November	1st to 10th	Night	20% 9% 32% 29% 10% 1	975
	11th to 20th	Night	19% 7% 34% 29% 9% 3	1000
	21st to end	Night	18% 9% 39% 26% 7% 1	1000
December	1st to 10th	Night	14% 8% 30% 32% 13% 2	1000
	11th to 20th	Night	18% 7% 33% 32% 8% 2	1000
	21st to end	Night	20% 5% 32% 29% 12% 1	1100

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