Mason City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mason City clear sky chart from 2005-11-06 to 2024-12-24.

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% 8% 3 8% 5% 4 5% 4 6% 7% 37%	101925
	Night	12% 9% 3 8% 5% 4 4 4 5% 6% 40%	98299
Transparency	Day	44% 6% 13% 24% 13% 1	105560
	Night	43% 5% 12% 24% 14% 2	102804
Seeing	Day	17% 10% 30% 27% 13% 3	16077
	Night	16% 10% 33% 31% 10% 1	26015

By Month

Percentage Cloud Cover SE (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	8% 15% 7% 21% 8% 6% 5% 3 4 5% 17%	2527
	11th to 20th	Day	7% 13% 4 11% 8% 7% 8% 5% 8% 6% 21%	2687
	21st to end	Day	12% 16% 8% 17% 7% 5% 5% 3 4 5% 17%	3135
February	1st to 10th	Day	8% 13% 5% 12% 8% 7% 5% 5% 6% 8% 25%	1710
	11th to 20th	Day	12% 12% 3 8% 6% 5% 6% 4 6% 8% 31%	1664
	21st to end	Day	15% 10% 3 11% 6% 4 4 4 6% 7% 30%	1498
March	1st to 10th	Day	14% 8% 3 7% 4 3 4 3 4 6% 43%	3396
	11th to 20th	Day	12% 7% 2 6% 4 3 4 5% 6% 7% 43%	3480
	21st to end	Day	24% 13% 5% 12% 6% 4 4 3 4 5% 20%	3840
April	1st to 10th	Day	19% 10% 4 8% 4 5% 4 3 6% 6% 30%	2280
	11th to 20th	Day	18% 10% 3 7% 5% 4 5% 4 5% 6% 34%	2254
	21st to end	Day	22% 10% 3 7% 5% 4 4 3 4 6% 31%	2427
May	1st to 10th	Day	18% 8% 3 7% 5% 5% 5% 3 6% 7% 33%	4160
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 5% 7% 44%	4399
	21st to end	Day	17% 8% 2 5% 4 4 5% 4 5% 7% 39%	4824
June	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 6% 8% 44%	2660
	11th to 20th	Day	12% 7% 2 6% 4 4 4 4 6% 9% 42%	2660
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 4 8% 9% 40%	2660
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 5% 8% 10% 37%	4440
	11th to 20th	Day	6% 3 2 5% 3 3 4 3 5% 8% 56%	4440
	21st to end	Day	5% 4 2 7% 4 5% 6% 5% 8% 10% 43%	4606
August	1st to 10th	Day	9% 6% 2 7% 4 5% 5% 4 6% 8% 43%	4104
	11th to 20th	Day	11% 6% 3 7% 4 5% 6% 5% 7% 9% 39%	4041
	21st to end	Day	7% 5% 2 6% 4 4 5% 4 6% 7% 49%	4276
September	1st to 10th	Day	12% 5% 2 6% 4 3 4 2 5% 7% 51%	2280
	11th to 20th	Day	10% 5% 2 6% 5% 3 3 3 6% 8% 48%	2252
	21st to end	Day	11% 6% 3 5% 4 4 5% 4 5% 7% 45%	1999
October	1st to 10th	Day	16% 7% 2 5% 3 4 4 3 4 7% 46%	1900
	11th to 20th	Day	16% 8% 3 6% 3 3 4 3 6% 6% 43%	1900
	21st to end	Day	16% 11% 3 6% 4 4 4 3 4 6% 39%	2090
November	1st to 10th	Day	11% 9% 3 5% 4 4 5% 3 6% 8% 42%	1731
	11th to 20th	Day	13% 10% 4 10% 6% 5% 5% 4 6% 6% 31%	1600
	21st to end	Day	13% 13% 4 8% 4 4 3 3 4 7% 37%	1600
December	1st to 10th	Day	12% 9% 4 12% 8% 5% 6% 5% 6% 8% 27%	1600
	11th to 20th	Day	12% 14% 5% 11% 6% 5% 5% 4 5% 7% 26%	1998
	21st to end	Day	20% 15% 8% 17% 5% 3 4 3 4 4 18%	2807
January	1st to 10th	Night	9% 13% 6% 23% 7% 4 4 3 4 5% 22%	4428
	11th to 20th	Night	7% 14% 5% 13% 7% 6% 7% 5% 9% 7% 21%	4280
	21st to end	Night	14% 15% 7% 15% 6% 5% 4 3 4 6% 20%	4532
February	1st to 10th	Night	9% 11% 5% 11% 7% 5% 5% 3 6% 6% 31%	2470
	11th to 20th	Night	9% 11% 3 8% 6% 5% 4 4 6% 6% 38%	2403
	21st to end	Night	13% 9% 3 8% 5% 5% 5% 3 4 6% 38%	1956
March	1st to 10th	Night	12% 8% 3 7% 3 3 4 3 4 6% 47%	3485
	11th to 20th	Night	10% 8% 3 6% 4 4 3 3 5% 8% 47%	3480
	21st to end	Night	26% 11% 3 11% 4 4 3 3 4 4 26%	3791
April	1st to 10th	Night	15% 10% 3 7% 5% 4 4 4 5% 5% 39%	1900
	11th to 20th	Night	19% 8% 2 6% 5% 3 4 4 5% 6% 38%	1875
	21st to end	Night	18% 8% 3 5% 3 4 3 3 5% 6% 40%	1748
May	1st to 10th	Night	17% 7% 3 6% 4 3 4 3 5% 5% 42%	2742
	11th to 20th	Night	13% 6% 2 6% 4 3 4 3 5% 6% 48%	2506
	21st to end	Night	12% 8% 2 6% 4 4 4 3 6% 6% 47%	2743
June	1st to 10th	Night	9% 4 1 5% 4 4 5% 6% 7% 8% 48%	1520
	11th to 20th	Night	11% 5% 2 6% 4 3 4 4 7% 9% 46%	1520
	21st to end	Night	10% 5% 2 5% 4 3 4 3 5% 10% 50%	1520
July	1st to 10th	Night	8% 6% 3 6% 4 3 4 4 6% 8% 48%	2530
	11th to 20th	Night	4 3 1 3 3 4 4 4 5% 9% 60%	2530
	21st to end	Night	5% 3 1 5% 3 4 4 4 7% 9% 54%	2955
August	1st to 10th	Night	8% 5% 2 6% 4 4 4 4 5% 8% 49%	2836
	11th to 20th	Night	12% 6% 1 4 3 3 4 3 5% 9% 52%	2798
	21st to end	Night	8% 5% 2 5% 4 4 4 3 5% 6% 54%	3382
September	1st to 10th	Night	9% 4 2 5% 3 3 3 4 4 5% 58%	1900
	11th to 20th	Night	11% 5% 2 5% 3 3 2 3 4 8% 53%	1926
	21st to end	Night	10% 7% 2 5% 3 3 3 3 4 6% 54%	2161
October	1st to 10th	Night	12% 6% 2 5% 3 3 4 3 5% 6% 50%	2280
	11th to 20th	Night	15% 6% 3 6% 3 4 4 3 4 6% 47%	2280
	21st to end	Night	15% 9% 3 7% 5% 4 4 4 5% 5% 40%	2508
November	1st to 10th	Night	12% 8% 2 6% 3 4 4 3 5% 6% 47%	2562
	11th to 20th	Night	12% 10% 4 9% 6% 4 4 3 5% 6% 38%	2800
	21st to end	Night	14% 10% 3 9% 4 4 4 3 4 6% 40%	2800
December	1st to 10th	Night	10% 10% 5% 11% 6% 5% 5% 4 5% 7% 32%	2800
	11th to 20th	Night	13% 11% 4 10% 7% 5% 4 5% 5% 7% 29%	3419
	21st to end	Night	20% 16% 6% 14% 6% 5% 3 3 4 4 19%	4933

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	69% 5% 10% 11% 6%	2528
	11th to 20th	Day	60% 4 11% 18% 7%	2687
	21st to end	Day	70% 4 11% 11% 4 1	3135
February	1st to 10th	Day	56% 5% 13% 17% 8% 1	1710
	11th to 20th	Day	50% 5% 12% 22% 8% 2	1673
	21st to end	Day	52% 5% 12% 19% 10% 2	1498
March	1st to 10th	Day	43% 5% 12% 26% 13% 2	3396
	11th to 20th	Day	38% 6% 11% 32% 12% 2	3480
	21st to end	Day	66% 6% 10% 13% 4	3840
April	1st to 10th	Day	53% 5% 13% 20% 9% 1	2280
	11th to 20th	Day	50% 6% 11% 19% 13% 1	2254
	21st to end	Day	53% 5% 11% 20% 10% 1	2427
May	1st to 10th	Day	49% 6% 13% 19% 13% 1	4198
	11th to 20th	Day	39% 6% 13% 29% 12% 1	4403
	21st to end	Day	44% 6% 11% 25% 13% 1	4837
June	1st to 10th	Day	35% 7% 14% 27% 16% 1	2660
	11th to 20th	Day	38% 7% 14% 22% 19% 1	2660
	21st to end	Day	37% 9% 16% 24% 13% 1	2660
July	1st to 10th	Day	39% 8% 18% 25% 8% 1	4371
	11th to 20th	Day	26% 6% 14% 33% 19% 2	4365
	21st to end	Day	30% 11% 17% 24% 16% 1	4461
August	1st to 10th	Day	37% 7% 14% 27% 13% 2	4090
	11th to 20th	Day	39% 8% 16% 27% 10%	4080
	21st to end	Day	32% 8% 15% 27% 18% 1	4275
September	1st to 10th	Day	33% 6% 13% 30% 17% 2	2280
	11th to 20th	Day	34% 6% 14% 32% 13%	2252
	21st to end	Day	38% 5% 11% 29% 17% 1	1999
October	1st to 10th	Day	25% 4 7% 36% 28% 1	3160
	11th to 20th	Day	31% 4 13% 27% 23% 2	3140
	21st to end	Day	42% 3 10% 31% 12% 1	3428
November	1st to 10th	Day	39% 6% 14% 24% 16% 2	1731
	11th to 20th	Day	51% 7% 12% 21% 10% 1	1600
	21st to end	Day	48% 4 16% 22% 9% 1	1600
December	1st to 10th	Day	54% 6% 14% 16% 9% 1	1600
	11th to 20th	Day	55% 5% 19% 14% 6%	1995
	21st to end	Day	70% 4 8% 12% 5%	2807
January	1st to 10th	Night	64% 5% 9% 14% 7% 1	4428
	11th to 20th	Night	58% 5% 12% 17% 8%	4280
	21st to end	Night	65% 4 10% 14% 5%	4532
February	1st to 10th	Night	53% 4 11% 21% 10% 1	2470
	11th to 20th	Night	45% 5% 13% 24% 11% 2	2404
	21st to end	Night	47% 4 12% 22% 13% 2	1956
March	1st to 10th	Night	38% 5% 11% 30% 15% 1	3485
	11th to 20th	Night	36% 4 9% 31% 17% 2	3480
	21st to end	Night	62% 5% 11% 15% 6% 1	3791
April	1st to 10th	Night	45% 5% 12% 24% 13% 1	1900
	11th to 20th	Night	46% 5% 11% 19% 17% 2	1875
	21st to end	Night	43% 5% 11% 25% 14% 2	1748
May	1st to 10th	Night	43% 6% 9% 19% 22% 1	2769
	11th to 20th	Night	37% 6% 9% 26% 17% 5%	2507
	21st to end	Night	37% 6% 10% 29% 16% 2	2751
June	1st to 10th	Night	30% 9% 14% 28% 16% 2	1520
	11th to 20th	Night	33% 8% 14% 21% 20% 4	1520
	21st to end	Night	30% 7% 16% 28% 17% 2	1520
July	1st to 10th	Night	32% 7% 19% 29% 12% 2	2490
	11th to 20th	Night	20% 7% 17% 36% 17% 2	2482
	21st to end	Night	24% 9% 17% 29% 19% 2	2861
August	1st to 10th	Night	32% 7% 13% 29% 17% 2	2826
	11th to 20th	Night	30% 7% 15% 33% 13% 1	2825
	21st to end	Night	30% 6% 16% 27% 18% 3	3382
September	1st to 10th	Night	28% 6% 11% 29% 25% 1	1900
	11th to 20th	Night	31% 6% 11% 31% 20% 1	1926
	21st to end	Night	31% 4 10% 30% 22% 2	2161
October	1st to 10th	Night	22% 4 8% 31% 33% 2	3800
	11th to 20th	Night	26% 4 12% 27% 25% 5%	3779
	21st to end	Night	44% 4 10% 25% 15% 2	4120
November	1st to 10th	Night	38% 5% 14% 25% 16% 3	2562
	11th to 20th	Night	47% 6% 12% 22% 12% 2	2800
	21st to end	Night	47% 5% 12% 25% 10% 1	2800
December	1st to 10th	Night	51% 5% 16% 19% 8% 1	2800
	11th to 20th	Night	53% 6% 15% 21% 5% 1	3421
	21st to end	Night	68% 5% 8% 13% 6%	4933

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	17% 11% 35% 25% 10% 1	270
	11th to 20th	Day	19% 11% 42% 24% 4 1	270
	21st to end	Day	19% 9% 39% 24% 7% 2	297
February	1st to 10th	Day	13% 20% 36% 25% 4 2	270
	11th to 20th	Day	16% 19% 39% 20% 5% 1	270
	21st to end	Day	23% 16% 36% 22% 4	225
March	1st to 10th	Day	18% 16% 41% 17% 7%	270
	11th to 20th	Day	22% 13% 33% 26% 5% 1	270
	21st to end	Day	33% 14% 28% 19% 6% 1	311
April	1st to 10th	Day	28% 14% 34% 20% 4	460
	11th to 20th	Day	26% 18% 27% 20% 7% 1	452
	21st to end	Day	27% 14% 30% 19% 8% 2	607
May	1st to 10th	Day	23% 13% 34% 22% 8% 2	653
	11th to 20th	Day	23% 12% 27% 24% 10% 4	675
	21st to end	Day	20% 9% 28% 25% 14% 4	734
June	1st to 10th	Day	10% 7% 27% 31% 20% 4	680
	11th to 20th	Day	13% 7% 30% 33% 14% 3	680
	21st to end	Day	12% 6% 35% 29% 14% 4	680
July	1st to 10th	Day	9% 4 19% 33% 24% 11%	671
	11th to 20th	Day	9% 3 29% 31% 21% 7%	668
	21st to end	Day	6% 2 25% 39% 21% 6%	739
August	1st to 10th	Day	9% 4 22% 35% 23% 8%	676
	11th to 20th	Day	11% 4 22% 31% 25% 7%	665
	21st to end	Day	10% 6% 23% 35% 21% 6%	596
September	1st to 10th	Day	15% 7% 24% 29% 20% 6%	490
	11th to 20th	Day	10% 5% 29% 33% 19% 5%	462
	21st to end	Day	13% 13% 31% 30% 10% 4	300
October	1st to 10th	Day	20% 10% 27% 24% 16% 4	300
	11th to 20th	Day	19% 19% 37% 18% 8% 1	300
	21st to end	Day	25% 15% 34% 18% 6% 2	330
November	1st to 10th	Day	19% 14% 35% 24% 7% 1	300
	11th to 20th	Day	19% 20% 36% 16% 9%	300
	21st to end	Day	22% 17% 38% 17% 5%	300
December	1st to 10th	Day	13% 14% 42% 24% 6% 1	300
	11th to 20th	Day	19% 14% 37% 21% 8% 1	300
	21st to end	Day	26% 15% 39% 18% 2	306
January	1st to 10th	Night	12% 15% 38% 27% 8%	950
	11th to 20th	Night	16% 12% 37% 28% 5% 1	950
	21st to end	Night	19% 12% 35% 26% 7%	1045
February	1st to 10th	Night	15% 12% 39% 28% 6% 1	950
	11th to 20th	Night	15% 14% 40% 26% 5% 1	929
	21st to end	Night	18% 14% 36% 26% 5% 1	700
March	1st to 10th	Night	20% 12% 34% 26% 7%	614
	11th to 20th	Night	19% 9% 39% 24% 9%	570
	21st to end	Night	24% 10% 35% 24% 6% 1	627
April	1st to 10th	Night	20% 14% 38% 24% 4	570
	11th to 20th	Night	23% 12% 34% 24% 6%	563
	21st to end	Night	22% 9% 35% 26% 6% 2	570
May	1st to 10th	Night	19% 8% 32% 32% 8%	570
	11th to 20th	Night	16% 9% 33% 31% 9% 1	561
	21st to end	Night	18% 6% 29% 33% 12% 1	617
June	1st to 10th	Night	10% 4 29% 42% 15% 1	570
	11th to 20th	Night	13% 3 28% 45% 10%	570
	21st to end	Night	12% 4 26% 42% 15% 1	570
July	1st to 10th	Night	7% 2 17% 42% 30% 2	555
	11th to 20th	Night	4 2 23% 43% 26% 2	552
	21st to end	Night	5% 2 18% 50% 21% 3	624
August	1st to 10th	Night	7% 2 17% 49% 24% 1	567
	11th to 20th	Night	10% 4 18% 41% 23% 4	564
	21st to end	Night	8% 3 22% 44% 20% 3	627
September	1st to 10th	Night	9% 4 23% 40% 20% 3	570
	11th to 20th	Night	14% 3 27% 37% 18% 2	570
	21st to end	Night	14% 9% 29% 33% 15% 1	641
October	1st to 10th	Night	14% 9% 32% 32% 13% 1	760
	11th to 20th	Night	18% 11% 35% 28% 7%	760
	21st to end	Night	19% 13% 33% 26% 8%	836
November	1st to 10th	Night	16% 12% 36% 29% 7% 1	830
	11th to 20th	Night	16% 15% 41% 21% 6%	1000
	21st to end	Night	18% 14% 36% 24% 7%	1000
December	1st to 10th	Night	16% 12% 41% 24% 7% 1	1000
	11th to 20th	Night	21% 11% 34% 28% 6%	1000
	21st to end	Night	24% 12% 34% 24% 6%	1063

Page generated at 2024-12-21 03:13:52. Version ac07

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