Oakdale
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oakdale clear sky chart from 2005-11-06 to 2024-01-12.

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	15% 9% 4 7% 6% 3 5% 5% 6% 7% 33%	74778
	Night	16% 10% 4 7% 6% 3 4 4 5% 6% 34%	74933
Transparency	Day	49% 6% 13% 20% 11% 1	74489
	Night	50% 5% 11% 21% 12% 1	74742
Seeing	Day	18% 10% 28% 25% 14% 6%	14004
	Night	20% 9% 28% 30% 12% 1	23547

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	17% 15% 7% 9% 9% 3 4 5% 5% 5% 21%	1517
	11th to 20th	Day	16% 19% 8% 13% 7% 4 4 3 4 5% 17%	1573
	21st to end	Day	16% 17% 8% 11% 8% 4 5% 5% 5% 5% 17%	1782
February	1st to 10th	Day	17% 14% 6% 11% 8% 4 5% 4 4 6% 19%	1620
	11th to 20th	Day	15% 12% 6% 12% 8% 3 5% 5% 6% 5% 23%	1623
	21st to end	Day	17% 14% 5% 9% 8% 4 4 4 4 5% 25%	1480
March	1st to 10th	Day	17% 11% 6% 9% 6% 4 5% 4 5% 6% 28%	1895
	11th to 20th	Day	14% 12% 5% 8% 5% 3 4 4 5% 6% 32%	1980
	21st to end	Day	20% 12% 5% 8% 7% 4 5% 4 4 5% 28%	2178
April	1st to 10th	Day	16% 11% 4 6% 6% 4 5% 5% 5% 7% 31%	2036
	11th to 20th	Day	19% 11% 3 5% 4 4 4 5% 5% 7% 33%	2312
	21st to end	Day	20% 10% 3 6% 5% 3 5% 4 5% 6% 33%	2340
May	1st to 10th	Day	18% 8% 3 6% 5% 4 5% 5% 5% 8% 34%	2340
	11th to 20th	Day	18% 8% 3 6% 6% 3 5% 4 5% 7% 35%	2301
	21st to end	Day	11% 5% 3 5% 5% 3 5% 6% 6% 9% 42%	2629
June	1st to 10th	Day	11% 6% 3 6% 6% 4 4 6% 5% 9% 41%	2566
	11th to 20th	Day	10% 6% 2 5% 5% 3 6% 6% 6% 9% 42%	2700
	21st to end	Day	12% 5% 2 5% 5% 3 5% 5% 8% 8% 41%	2700
July	1st to 10th	Day	9% 4 2 5% 6% 4 5% 5% 6% 9% 46%	2601
	11th to 20th	Day	9% 5% 2 5% 6% 3 5% 5% 7% 10% 42%	2453
	21st to end	Day	9% 5% 3 5% 5% 4 5% 6% 8% 11% 39%	2547
August	1st to 10th	Day	8% 5% 2 4 6% 5% 6% 6% 8% 10% 40%	2327
	11th to 20th	Day	10% 6% 2 6% 5% 4 6% 7% 7% 10% 37%	2303
	21st to end	Day	11% 7% 2 6% 6% 3 5% 6% 5% 8% 43%	2574
September	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 6% 6% 9% 40%	2052
	11th to 20th	Day	10% 5% 2 5% 5% 3 5% 5% 6% 10% 44%	1980
	21st to end	Day	16% 7% 3 5% 5% 3 4 5% 5% 8% 37%	1980
October	1st to 10th	Day	14% 7% 3 6% 5% 3 5% 5% 6% 7% 39%	1872
	11th to 20th	Day	19% 9% 3 7% 6% 5% 5% 4 5% 7% 31%	1800
	21st to end	Day	22% 10% 4 7% 6% 4 5% 4 5% 7% 27%	1908
November	1st to 10th	Day	13% 9% 5% 7% 7% 3 5% 5% 5% 7% 34%	1672
	11th to 20th	Day	15% 12% 5% 7% 5% 3 5% 6% 6% 7% 30%	1640
	21st to end	Day	21% 12% 5% 8% 7% 3 5% 5% 5% 6% 23%	1520
December	1st to 10th	Day	16% 14% 6% 11% 7% 3 5% 5% 4 7% 21%	1520
	11th to 20th	Day	18% 15% 7% 9% 6% 4 4 4 4 7% 21%	1910
	21st to end	Day	28% 20% 6% 9% 7% 3 4 3 4 4 11%	2547
January	1st to 10th	Night	18% 12% 6% 10% 7% 4 5% 4 4 6% 23%	2648
	11th to 20th	Night	20% 17% 7% 9% 6% 3 4 5% 4 5% 19%	2422
	21st to end	Night	14% 16% 7% 10% 9% 4 5% 4 5% 4 21%	2574
February	1st to 10th	Night	17% 16% 5% 9% 8% 3 5% 4 5% 5% 22%	2340
	11th to 20th	Night	17% 13% 7% 8% 6% 3 5% 4 5% 6% 26%	2223
	21st to end	Night	20% 11% 5% 8% 7% 3 5% 5% 4 5% 27%	1776
March	1st to 10th	Night	15% 11% 5% 8% 6% 4 5% 4 5% 7% 31%	2064
	11th to 20th	Night	15% 9% 3 5% 6% 3 4 5% 5% 7% 37%	1980
	21st to end	Night	19% 9% 4 8% 6% 3 5% 4 4 5% 33%	2178
April	1st to 10th	Night	16% 10% 3 6% 6% 3 4 5% 5% 6% 35%	1937
	11th to 20th	Night	18% 8% 3 5% 5% 3 4 3 5% 8% 38%	1597
	21st to end	Night	17% 10% 3 6% 5% 4 3 4 5% 7% 37%	1620
May	1st to 10th	Night	17% 7% 3 6% 6% 3 4 5% 7% 7% 34%	1620
	11th to 20th	Night	14% 7% 3 6% 5% 3 5% 4 6% 8% 38%	1592
	21st to end	Night	10% 5% 2 4 5% 3 6% 5% 5% 7% 49%	1642
June	1st to 10th	Night	11% 4 3 4 5% 3 5% 4 6% 9% 47%	1388
	11th to 20th	Night	10% 5% 1 5% 4 3 6% 5% 6% 10% 46%	1260
	21st to end	Night	10% 5% 3 4 5% 2 5% 4 5% 9% 49%	1260
July	1st to 10th	Night	6% 4 2 6% 4 3 3 4 5% 8% 55%	1354
	11th to 20th	Night	8% 4 2 5% 4 3 4 5% 7% 9% 49%	1504
	21st to end	Night	8% 3 2 4 5% 3 4 5% 9% 10% 48%	1771
August	1st to 10th	Night	7% 4 2 5% 5% 3 5% 5% 6% 9% 49%	1611
	11th to 20th	Night	7% 4 2 5% 5% 4 5% 6% 7% 8% 48%	1598
	21st to end	Night	9% 4 2 5% 3 3 5% 5% 5% 8% 51%	1782
September	1st to 10th	Night	9% 7% 2 5% 5% 3 5% 4 6% 7% 47%	1887
	11th to 20th	Night	9% 5% 2 4 4 2 3 4 5% 7% 54%	1980
	21st to end	Night	14% 6% 3 6% 6% 3 5% 4 4 7% 42%	1980
October	1st to 10th	Night	13% 7% 3 6% 5% 4 3 4 5% 6% 45%	2088
	11th to 20th	Night	20% 8% 3 6% 5% 3 4 4 5% 5% 36%	2160
	21st to end	Night	24% 7% 4 6% 7% 3 4 4 5% 6% 30%	2444
November	1st to 10th	Night	14% 8% 3 5% 6% 3 4 4 6% 7% 40%	2406
	11th to 20th	Night	17% 10% 4 7% 7% 3 5% 4 5% 7% 31%	2536
	21st to end	Night	21% 13% 4 7% 5% 3 4 4 5% 6% 29%	2660
December	1st to 10th	Night	18% 16% 6% 8% 7% 4 5% 4 5% 6% 21%	2660
	11th to 20th	Night	16% 16% 5% 9% 7% 4 4 5% 4 6% 25%	3285
	21st to end	Night	26% 21% 7% 9% 5% 3 4 4 3 4 13%	5106

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	64% 4 11% 13% 7% 1	1518
	11th to 20th	Day	71% 4 11% 9% 5%	1573
	21st to end	Day	68% 6% 8% 12% 6%	1782
February	1st to 10th	Day	67% 5% 10% 13% 5%	1620
	11th to 20th	Day	62% 5% 10% 15% 7% 1	1632
	21st to end	Day	63% 4 11% 15% 6% 1	1480
March	1st to 10th	Day	57% 5% 12% 16% 9% 1	1895
	11th to 20th	Day	52% 4 11% 19% 12% 2	1980
	21st to end	Day	59% 4 9% 18% 8% 1	2178
April	1st to 10th	Day	51% 5% 12% 20% 11% 1	2036
	11th to 20th	Day	50% 5% 11% 19% 14% 2	2312
	21st to end	Day	51% 5% 13% 18% 12% 2	2340
May	1st to 10th	Day	48% 6% 11% 21% 11% 2	2340
	11th to 20th	Day	48% 6% 13% 18% 13% 2	2305
	21st to end	Day	38% 7% 14% 23% 16% 2	2629
June	1st to 10th	Day	39% 5% 13% 27% 13% 2	2566
	11th to 20th	Day	36% 7% 15% 23% 17% 2	2700
	21st to end	Day	36% 8% 13% 25% 17% 1	2700
July	1st to 10th	Day	34% 6% 9% 28% 19% 3	2532
	11th to 20th	Day	34% 6% 15% 27% 16% 2	2378
	21st to end	Day	36% 8% 15% 22% 16% 2	2405
August	1st to 10th	Day	35% 8% 16% 27% 13% 1	2314
	11th to 20th	Day	38% 9% 15% 25% 11% 2	2303
	21st to end	Day	38% 7% 12% 26% 16% 1	2574
September	1st to 10th	Day	40% 7% 15% 23% 13% 1	2052
	11th to 20th	Day	35% 7% 12% 32% 14%	1980
	21st to end	Day	44% 6% 14% 25% 12% 1	1980
October	1st to 10th	Day	43% 7% 12% 24% 13% 1	1872
	11th to 20th	Day	52% 5% 14% 20% 9% 1	1800
	21st to end	Day	56% 6% 13% 17% 8%	1908
November	1st to 10th	Day	49% 6% 11% 22% 10% 2	1672
	11th to 20th	Day	51% 5% 16% 18% 9% 1	1640
	21st to end	Day	62% 5% 12% 16% 5%	1520
December	1st to 10th	Day	62% 6% 14% 14% 4	1520
	11th to 20th	Day	64% 4 14% 13% 5%	1906
	21st to end	Day	78% 4 10% 6% 2	2547
January	1st to 10th	Night	62% 4 9% 15% 8% 1	2648
	11th to 20th	Night	68% 5% 10% 12% 5%	2422
	21st to end	Night	64% 5% 10% 15% 5%	2574
February	1st to 10th	Night	64% 6% 10% 14% 6% 1	2340
	11th to 20th	Night	59% 3 10% 16% 10% 1	2225
	21st to end	Night	59% 4 10% 18% 8% 1	1776
March	1st to 10th	Night	53% 5% 10% 21% 9% 1	2064
	11th to 20th	Night	46% 4 11% 24% 13% 2	1980
	21st to end	Night	53% 4 8% 22% 12% 1	2178
April	1st to 10th	Night	49% 5% 10% 20% 13% 2	1937
	11th to 20th	Night	46% 5% 10% 21% 17% 1	1597
	21st to end	Night	47% 5% 9% 20% 15% 4	1620
May	1st to 10th	Night	48% 6% 10% 19% 13% 4	1620
	11th to 20th	Night	44% 5% 11% 20% 17% 3	1593
	21st to end	Night	34% 7% 13% 27% 17% 3	1643
June	1st to 10th	Night	34% 6% 11% 29% 18% 2	1388
	11th to 20th	Night	34% 6% 14% 23% 20% 2	1260
	21st to end	Night	33% 6% 12% 27% 20% 2	1260
July	1st to 10th	Night	28% 5% 9% 30% 23% 4	1314
	11th to 20th	Night	31% 6% 13% 30% 18% 2	1456
	21st to end	Night	28% 8% 17% 25% 19% 3	1672
August	1st to 10th	Night	31% 6% 16% 31% 15% 2	1600
	11th to 20th	Night	30% 7% 15% 31% 14% 2	1598
	21st to end	Night	31% 6% 12% 31% 19% 1	1782
September	1st to 10th	Night	36% 6% 13% 26% 16% 2	1887
	11th to 20th	Night	29% 6% 13% 32% 19% 1	1980
	21st to end	Night	41% 5% 11% 28% 13% 1	1980
October	1st to 10th	Night	41% 5% 11% 23% 19% 1	2088
	11th to 20th	Night	50% 4 11% 21% 13% 1	2160
	21st to end	Night	55% 5% 11% 18% 10% 1	2444
November	1st to 10th	Night	43% 6% 11% 26% 13% 1	2406
	11th to 20th	Night	52% 5% 12% 21% 9% 1	2536
	21st to end	Night	56% 4 15% 18% 6%	2660
December	1st to 10th	Night	63% 5% 13% 14% 4	2660
	11th to 20th	Night	59% 6% 14% 15% 7%	3288
	21st to end	Night	76% 4 10% 7% 3	5106

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	23% 20% 32% 16% 9% 1	270
	11th to 20th	Day	25% 13% 42% 14% 5% 1	245
	21st to end	Day	28% 14% 35% 18% 5% 1	264
February	1st to 10th	Day	25% 20% 41% 12% 2	240
	11th to 20th	Day	24% 21% 37% 16% 1	240
	21st to end	Day	28% 24% 33% 14% 1	198
March	1st to 10th	Day	27% 15% 33% 19% 5% 1	335
	11th to 20th	Day	21% 14% 32% 25% 6% 1	420
	21st to end	Day	29% 13% 30% 22% 6% 1	462
April	1st to 10th	Day	19% 14% 33% 24% 9%	420
	11th to 20th	Day	28% 13% 25% 18% 10% 6%	412
	21st to end	Day	25% 12% 29% 22% 10% 2	420
May	1st to 10th	Day	23% 10% 28% 26% 10% 4	423
	11th to 20th	Day	20% 8% 28% 26% 13% 6%	447
	21st to end	Day	16% 7% 21% 28% 20% 8%	485
June	1st to 10th	Day	12% 7% 29% 30% 18% 4	496
	11th to 20th	Day	13% 6% 30% 32% 15% 4	630
	21st to end	Day	13% 7% 28% 33% 15% 4	630
July	1st to 10th	Day	9% 4 22% 31% 24% 11%	621
	11th to 20th	Day	11% 5% 24% 30% 20% 9%	551
	21st to end	Day	10% 3 22% 29% 25% 11%	488
August	1st to 10th	Day	9% 3 19% 27% 26% 16%	446
	11th to 20th	Day	12% 5% 15% 31% 22% 15%	439
	21st to end	Day	12% 5% 20% 27% 26% 11%	495
September	1st to 10th	Day	13% 4 20% 29% 23% 11%	450
	11th to 20th	Day	10% 3 19% 26% 30% 13%	450
	21st to end	Day	16% 12% 20% 25% 18% 9%	450
October	1st to 10th	Day	19% 7% 24% 24% 19% 7%	450
	11th to 20th	Day	20% 14% 30% 26% 9% 2	450
	21st to end	Day	27% 11% 38% 17% 5% 1	423
November	1st to 10th	Day	15% 18% 37% 20% 8% 3	270
	11th to 20th	Day	24% 14% 32% 18% 10% 1	237
	21st to end	Day	24% 18% 38% 15% 4 1	180
December	1st to 10th	Day	25% 14% 36% 16% 9% 1	180
	11th to 20th	Day	27% 20% 35% 17% 2	180
	21st to end	Day	33% 16% 30% 17% 3	207
January	1st to 10th	Night	25% 13% 37% 18% 6% 1	950
	11th to 20th	Night	31% 12% 30% 23% 4	785
	21st to end	Night	24% 10% 31% 29% 7%	792
February	1st to 10th	Night	25% 14% 35% 23% 3	720
	11th to 20th	Night	25% 14% 29% 26% 6%	703
	21st to end	Night	27% 12% 37% 21% 3	592
March	1st to 10th	Night	20% 11% 35% 28% 5%	720
	11th to 20th	Night	18% 11% 38% 25% 7% 1	720
	21st to end	Night	22% 11% 29% 28% 9% 1	792
April	1st to 10th	Night	21% 14% 32% 28% 5% 1	706
	11th to 20th	Night	22% 8% 32% 27% 10% 1	533
	21st to end	Night	22% 6% 34% 29% 8%	540
May	1st to 10th	Night	18% 7% 29% 34% 11% 1	540
	11th to 20th	Night	17% 5% 27% 37% 13% 1	531
	21st to end	Night	12% 3 21% 44% 19% 1	482
June	1st to 10th	Night	13% 2 28% 42% 15%	360
	11th to 20th	Night	10% 4 22% 49% 14% 1	360
	21st to end	Night	11% 5% 24% 43% 16% 1	360
July	1st to 10th	Night	7% 3 16% 43% 28% 3	439
	11th to 20th	Night	9% 2 20% 41% 25% 3	522
	21st to end	Night	9% 2 16% 46% 25% 2	591
August	1st to 10th	Night	7% 2 12% 42% 31% 4	537
	11th to 20th	Night	8% 1 15% 39% 33% 5%	534
	21st to end	Night	12% 2 15% 38% 30% 3	594
September	1st to 10th	Night	11% 4 19% 36% 25% 5%	702
	11th to 20th	Night	10% 4 18% 35% 28% 5%	720
	21st to end	Night	16% 7% 18% 35% 18% 5%	720
October	1st to 10th	Night	15% 7% 24% 33% 18% 3	720
	11th to 20th	Night	23% 9% 28% 28% 10% 1	720
	21st to end	Night	26% 11% 29% 29% 5%	792
November	1st to 10th	Night	18% 10% 28% 29% 14% 1	740
	11th to 20th	Night	21% 13% 34% 23% 7% 1	760
	21st to end	Night	28% 12% 30% 23% 8%	760
December	1st to 10th	Night	28% 12% 34% 19% 7%	760
	11th to 20th	Night	23% 15% 36% 23% 4	760
	21st to end	Night	32% 12% 31% 23% 3	990

Page generated at 2024-01-09 16:24:22. Version ac07

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