Merle K. (Mudhole) Smith Airport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Merle K. (Mudhole) Smith Airport clear sky chart from 2005-11-06 to 2025-12-03.

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	35% 16% 4 8% 4 4 3 3 3 4 16%	132343
	Night	32% 19% 4 7% 4 3 3 2 3 4 19%	127021
Transparency	Day	70% 7% 10% 8% 4 1	132001
	Night	69% 6% 8% 9% 6% 2	126944
Seeing	Day	38% 8% 13% 18% 17% 5%	18720
	Night	38% 9% 16% 18% 14% 4	23593

By Month

Percentage Cloud Cover NW (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	30% 21% 4 6% 3 2 2 2 4 4 20%	2259
	11th to 20th	Day	32% 19% 3 5% 2 2 2 1 2 3 30%	2516
	21st to end	Day	31% 24% 3 9% 3 3 2 2 2 2 19%	2992
February	1st to 10th	Day	19% 20% 4 7% 3 5% 3 2 3 4 31%	1441
	11th to 20th	Day	30% 23% 5% 8% 3 3 3 2 3 3 18%	1559
	21st to end	Day	17% 19% 3 7% 3 3 3 2 3 4 34%	1412
March	1st to 10th	Day	22% 27% 5% 8% 4 3 3 3 3 3 19%	4474
	11th to 20th	Day	18% 27% 5% 9% 5% 4 4 3 4 4 17%	4744
	21st to end	Day	20% 20% 5% 9% 5% 5% 4 4 4 5% 18%	5821
April	1st to 10th	Day	23% 25% 5% 8% 5% 4 3 3 3 3 19%	2524
	11th to 20th	Day	19% 21% 4 9% 5% 4 4 3 3 4 26%	2635
	21st to end	Day	25% 19% 5% 8% 5% 3 3 4 4 4 19%	2920
May	1st to 10th	Day	38% 23% 4 9% 5% 3 3 2 3 3 8%	6800
	11th to 20th	Day	28% 18% 5% 10% 6% 4 3 2 4 4 15%	7328
	21st to end	Day	35% 14% 4 9% 5% 4 4 3 4 4 13%	8409
June	1st to 10th	Day	38% 14% 3 8% 5% 3 4 2 3 4 16%	3400
	11th to 20th	Day	31% 12% 3 7% 6% 4 4 4 4 5% 19%	3594
	21st to end	Day	39% 13% 3 7% 5% 3 3 3 4 4 17%	3600
July	1st to 10th	Day	44% 14% 4 9% 6% 4 3 3 3 2 8%	7943
	11th to 20th	Day	38% 11% 4 9% 5% 4 4 3 5% 5% 11%	7700
	21st to end	Day	37% 11% 4 8% 5% 4 4 3 4 5% 16%	7899
August	1st to 10th	Day	50% 10% 3 6% 4 3 2 2 3 3 14%	5024
	11th to 20th	Day	44% 7% 3 7% 4 4 4 3 4 5% 14%	4623
	21st to end	Day	48% 9% 3 7% 4 3 3 3 4 4 13%	4874
September	1st to 10th	Day	56% 9% 3 5% 4 2 3 1 2 3 13%	2566
	11th to 20th	Day	52% 9% 2 5% 3 2 3 2 3 4 15%	2295
	21st to end	Day	45% 9% 3 6% 3 4 3 3 3 4 17%	2200
October	1st to 10th	Day	43% 12% 5% 8% 4 4 3 2 3 3 12%	3176
	11th to 20th	Day	31% 12% 4 8% 4 3 3 2 3 4 27%	2924
	21st to end	Day	32% 12% 3 7% 5% 4 3 2 4 4 24%	2829
November	1st to 10th	Day	31% 17% 4 9% 4 3 3 2 2 3 22%	1441
	11th to 20th	Day	24% 14% 3 8% 5% 3 3 4 4 4 27%	1360
	21st to end	Day	28% 21% 5% 6% 3 3 2 3 4 4 21%	1050
December	1st to 10th	Day	49% 17% 2 6% 3 2 2 1 2 3 15%	1640
	11th to 20th	Day	28% 29% 5% 7% 4 2 2 2 3 3 13%	1885
	21st to end	Day	26% 25% 4 8% 3 3 2 2 3 3 20%	2486
January	1st to 10th	Night	29% 22% 4 7% 3 2 2 2 3 4 22%	7686
	11th to 20th	Night	31% 22% 4 5% 3 2 2 2 2 2 26%	7391
	21st to end	Night	30% 24% 4 9% 4 3 2 2 2 2 17%	7986
February	1st to 10th	Night	19% 20% 3 7% 4 3 3 2 4 4 31%	2956
	11th to 20th	Night	29% 25% 4 8% 4 3 2 2 3 3 18%	2728
	21st to end	Night	17% 17% 3 7% 4 3 4 4 4 5% 32%	2215
March	1st to 10th	Night	21% 27% 4 8% 4 4 2 2 3 3 21%	5380
	11th to 20th	Night	16% 26% 6% 10% 5% 4 3 3 4 4 20%	5214
	21st to end	Night	20% 21% 5% 9% 4 4 4 3 4 5% 22%	5109
April	1st to 10th	Night	22% 22% 5% 8% 5% 4 3 3 4 4 20%	1876
	11th to 20th	Night	18% 18% 4 6% 6% 4 3 4 4 4 28%	1713
	21st to end	Night	24% 17% 3 9% 5% 4 3 3 4 4 24%	1480
May	1st to 10th	Night	38% 22% 4 7% 3 2 3 2 3 3 12%	3180
	11th to 20th	Night	26% 18% 4 7% 5% 5% 4 3 4 4 19%	2579
	21st to end	Night	34% 13% 4 7% 5% 4 3 3 4 5% 17%	2466
June	1st to 10th	Night	37% 9% 3 9% 5% 4 4 2 4 3 21%	1000
	11th to 20th	Night	28% 11% 3 5% 5% 5% 4 5% 5% 6% 25%	803
	21st to end	Night	35% 10% 3 7% 5% 4 4 4 5% 5% 20%	800
July	1st to 10th	Night	46% 12% 3 8% 5% 4 3 2 3 4 10%	2013
	11th to 20th	Night	41% 10% 3 7% 5% 4 5% 4 5% 5% 13%	2260
	21st to end	Night	38% 12% 2 6% 4 3 3 3 4 5% 18%	2966
August	1st to 10th	Night	47% 9% 3 6% 4 4 4 3 3 4 15%	2135
	11th to 20th	Night	46% 8% 2 5% 5% 3 3 3 4 4 17%	2434
	21st to end	Night	51% 9% 2 5% 3 3 3 2 4 3 14%	3035
September	1st to 10th	Night	51% 9% 3 6% 4 3 3 3 3 3 13%	1831
	11th to 20th	Night	49% 11% 2 5% 3 3 3 2 3 3 16%	2105
	21st to end	Night	45% 11% 3 6% 3 2 3 2 4 4 18%	2200
October	1st to 10th	Night	46% 13% 3 8% 4 3 3 2 3 2 13%	4007
	11th to 20th	Night	33% 13% 3 7% 4 3 3 2 3 3 26%	4224
	21st to end	Night	35% 14% 3 6% 4 3 4 3 4 5% 19%	4971
November	1st to 10th	Night	31% 19% 3 7% 4 3 3 2 3 3 21%	3077
	11th to 20th	Night	25% 16% 3 6% 3 3 3 3 4 4 30%	3257
	21st to end	Night	29% 20% 4 7% 4 3 3 2 3 3 22%	3570
December	1st to 10th	Night	48% 15% 3 6% 3 3 3 2 3 3 12%	5584
	11th to 20th	Night	28% 25% 4 8% 4 3 3 2 3 3 15%	6320
	21st to end	Night	27% 28% 5% 8% 4 3 3 2 3 3 14%	8470

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	65% 6% 7% 9% 10% 3	2259
	11th to 20th	Day	63% 3 4 13% 8% 9%	2534
	21st to end	Day	72% 4 3 6% 9% 6%	2992
February	1st to 10th	Day	59% 5% 9% 12% 8% 7%	1441
	11th to 20th	Day	74% 4 5% 6% 8% 2	1566
	21st to end	Day	54% 6% 8% 12% 14% 6%	1412
March	1st to 10th	Day	69% 6% 6% 7% 7% 7%	4474
	11th to 20th	Day	65% 8% 8% 11% 6% 2	4744
	21st to end	Day	63% 9% 12% 6% 8% 2	5821
April	1st to 10th	Day	69% 6% 9% 11% 3 2	2524
	11th to 20th	Day	60% 5% 11% 16% 7%	2635
	21st to end	Day	66% 6% 10% 11% 6%	2920
May	1st to 10th	Day	78% 9% 6% 7% 1	6800
	11th to 20th	Day	65% 11% 11% 11% 3	7331
	21st to end	Day	70% 9% 11% 8% 1	8410
June	1st to 10th	Day	72% 7% 11% 7% 3	3400
	11th to 20th	Day	65% 10% 14% 8% 2	3594
	21st to end	Day	71% 8% 14% 7%	3600
July	1st to 10th	Day	81% 8% 6% 4	7858
	11th to 20th	Day	73% 9% 15% 2	7607
	21st to end	Day	70% 8% 17% 6%	7678
August	1st to 10th	Day	76% 7% 8% 9%	5005
	11th to 20th	Day	69% 10% 13% 6% 2	4668
	21st to end	Day	75% 7% 10% 7% 1	4873
September	1st to 10th	Day	78% 5% 8% 7% 2	2566
	11th to 20th	Day	75% 6% 8% 9% 2	2295
	21st to end	Day	71% 7% 9% 9% 5%	2200
October	1st to 10th	Day	77% 6% 8% 6% 2	3176
	11th to 20th	Day	62% 6% 10% 8% 11% 4	2924
	21st to end	Day	63% 7% 10% 9% 10% 1	2829
November	1st to 10th	Day	70% 6% 6% 7% 8% 4	1441
	11th to 20th	Day	60% 6% 8% 15% 9% 2	1360
	21st to end	Day	65% 7% 7% 12% 8% 1	1050
December	1st to 10th	Day	79% 4 5% 7% 5%	1640
	11th to 20th	Day	75% 6% 8% 7% 4	1888
	21st to end	Day	68% 6% 7% 9% 7% 4	2486
January	1st to 10th	Night	67% 5% 5% 7% 12% 5%	7686
	11th to 20th	Night	66% 4 4 9% 9% 8%	7436
	21st to end	Night	72% 6% 5% 6% 7% 5%	7986
February	1st to 10th	Night	58% 5% 7% 14% 9% 8%	2956
	11th to 20th	Night	73% 4 5% 6% 8% 3	2732
	21st to end	Night	53% 7% 8% 12% 13% 7%	2215
March	1st to 10th	Night	67% 5% 6% 8% 10% 4	5380
	11th to 20th	Night	64% 7% 8% 11% 8% 2	5216
	21st to end	Night	60% 7% 12% 11% 8% 2	5109
April	1st to 10th	Night	67% 6% 9% 11% 6% 1	1876
	11th to 20th	Night	58% 6% 10% 18% 7% 1	1713
	21st to end	Night	64% 8% 10% 12% 6%	1480
May	1st to 10th	Night	78% 7% 7% 8%	3177
	11th to 20th	Night	64% 9% 14% 10% 3	2580
	21st to end	Night	64% 11% 14% 9% 1	2466
June	1st to 10th	Night	68% 8% 13% 8% 3	1000
	11th to 20th	Night	61% 11% 17% 9% 2	803
	21st to end	Night	63% 12% 17% 8%	800
July	1st to 10th	Night	80% 8% 8% 4	1989
	11th to 20th	Night	73% 11% 13% 2	2230
	21st to end	Night	67% 9% 17% 7%	2883
August	1st to 10th	Night	73% 10% 10% 7% 1	2129
	11th to 20th	Night	69% 10% 12% 8% 1	2455
	21st to end	Night	75% 7% 10% 6% 1	3035
September	1st to 10th	Night	78% 8% 8% 5% 2	1831
	11th to 20th	Night	74% 7% 8% 8% 2	2105
	21st to end	Night	72% 7% 8% 10% 3	2200
October	1st to 10th	Night	77% 6% 7% 6% 3	4007
	11th to 20th	Night	64% 6% 9% 9% 12% 1	4224
	21st to end	Night	68% 7% 9% 11% 4 1	4971
November	1st to 10th	Night	69% 6% 6% 7% 8% 4	3077
	11th to 20th	Night	58% 6% 8% 14% 11% 2	3257
	21st to end	Night	68% 5% 8% 11% 7% 2	3570
December	1st to 10th	Night	79% 5% 5% 7% 3 1	5584
	11th to 20th	Night	73% 6% 9% 8% 3	6316
	21st to end	Night	74% 6% 5% 7% 5% 3	8470

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	27% 15% 21% 25% 8% 4	100
	11th to 20th	Day	38% 11% 22% 18% 10% 1	218
	21st to end	Day	43% 13% 18% 18% 6% 1	330
February	1st to 10th	Day	27% 12% 21% 19% 17% 4	380
	11th to 20th	Day	38% 12% 22% 15% 10% 2	395
	21st to end	Day	26% 16% 27% 19% 10% 2	331
March	1st to 10th	Day	28% 11% 25% 20% 15% 2	400
	11th to 20th	Day	28% 11% 24% 17% 15% 6%	400
	21st to end	Day	27% 10% 17% 22% 17% 9%	590
April	1st to 10th	Day	30% 11% 21% 20% 13% 4	663
	11th to 20th	Day	26% 8% 15% 21% 22% 7%	690
	21st to end	Day	33% 10% 9% 17% 25% 6%	700
May	1st to 10th	Day	43% 12% 14% 12% 16% 4	703
	11th to 20th	Day	32% 6% 12% 23% 22% 6%	725
	21st to end	Day	38% 6% 10% 20% 21% 5%	790
June	1st to 10th	Day	39% 7% 9% 15% 22% 8%	730
	11th to 20th	Day	32% 4 9% 22% 24% 8%	924
	21st to end	Day	40% 3 10% 15% 22% 9%	930
July	1st to 10th	Day	36% 5% 9% 18% 26% 7%	833
	11th to 20th	Day	43% 7% 7% 17% 20% 6%	718
	21st to end	Day	42% 5% 10% 17% 17% 8%	794
August	1st to 10th	Day	49% 5% 8% 17% 16% 5%	726
	11th to 20th	Day	48% 6% 9% 18% 15% 5%	715
	21st to end	Day	48% 5% 10% 15% 17% 4	803
September	1st to 10th	Day	54% 8% 8% 13% 13% 4	711
	11th to 20th	Day	53% 6% 7% 13% 15% 6%	515
	21st to end	Day	44% 10% 13% 15% 11% 8%	420
October	1st to 10th	Day	44% 10% 15% 14% 10% 7%	420
	11th to 20th	Day	43% 8% 14% 20% 11% 3	420
	21st to end	Day	39% 10% 18% 20% 11% 2	462
November	1st to 10th	Day	36% 13% 20% 19% 12%	425
	11th to 20th	Day	32% 9% 23% 21% 14% 2	337
	21st to end	Day	40% 13% 21% 15% 9% 3	110
December	1st to 10th	Day	43% 10% 16% 22% 10%	102
	11th to 20th	Day	40% 18% 20% 17% 5%	100
	21st to end	Day	35% 15% 24% 16% 8% 1	110
January	1st to 10th	Night	32% 11% 20% 23% 12% 1	900
	11th to 20th	Night	39% 14% 21% 17% 8% 1	900
	21st to end	Night	40% 13% 18% 20% 8% 1	990
February	1st to 10th	Night	28% 13% 20% 21% 16% 1	900
	11th to 20th	Night	41% 10% 22% 16% 9% 1	884
	21st to end	Night	26% 12% 28% 20% 11% 3	738
March	1st to 10th	Night	28% 11% 25% 24% 10% 2	700
	11th to 20th	Night	25% 11% 24% 19% 16% 4	652
	21st to end	Night	29% 8% 16% 21% 20% 7%	660
April	1st to 10th	Night	32% 10% 16% 20% 15% 7%	600
	11th to 20th	Night	26% 8% 14% 20% 27% 6%	593
	21st to end	Night	30% 7% 12% 17% 27% 7%	600
May	1st to 10th	Night	42% 9% 8% 16% 19% 6%	600
	11th to 20th	Night	30% 7% 10% 20% 25% 9%	349
	21st to end	Night	35% 4 6% 15% 29% 11%	217
June	1st to 10th	Night	35% 5% 11% 13% 23% 14%	200
	11th to 20th	Night	31% 3 12% 12% 28% 15%	200
	21st to end	Night	34% 4 10% 11% 30% 13%	200
July	1st to 10th	Night	38% 5% 8% 14% 26% 9%	195
	11th to 20th	Night	38% 5% 5% 16% 24% 12%	194
	21st to end	Night	45% 4 8% 14% 18% 11%	436
August	1st to 10th	Night	47% 3 7% 16% 20% 8%	501
	11th to 20th	Night	52% 3 6% 15% 15% 7%	594
	21st to end	Night	48% 6% 7% 15% 17% 7%	660
September	1st to 10th	Night	51% 6% 9% 14% 16% 5%	600
	11th to 20th	Night	52% 6% 9% 13% 13% 8%	600
	21st to end	Night	49% 8% 8% 16% 15% 4	600
October	1st to 10th	Night	48% 6% 12% 15% 15% 3	789
	11th to 20th	Night	42% 9% 15% 20% 12% 2	910
	21st to end	Night	40% 10% 15% 21% 13% 1	1001
November	1st to 10th	Night	40% 12% 19% 18% 10%	930
	11th to 20th	Night	32% 12% 23% 23% 9% 1	950
	21st to end	Night	40% 13% 18% 19% 10% 1	950
December	1st to 10th	Night	47% 8% 18% 18% 8% 2	910
	11th to 20th	Night	36% 12% 23% 21% 8% 2	900
	21st to end	Night	43% 13% 19% 15% 9% 1	990

Page generated at 2025-11-29 22:00:52. Version ac07

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