Watrous
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Watrous clear sky chart from 2005-11-06 to 2024-02-05.

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	10% 8% 3 7% 6% 4 6% 5% 6% 8% 36%	77540
	Night	8% 8% 4 8% 7% 4 5% 5% 6% 8% 36%	81258
Transparency	Day	46% 7% 16% 22% 9% 1	77246
	Night	46% 7% 15% 22% 9% 1	81132
Seeing	Day	13% 8% 28% 30% 16% 4	14759
	Night	12% 7% 30% 36% 14% 2	24340

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	6% 14% 6% 14% 10% 5% 7% 6% 4 6% 22%	2133
	11th to 20th	Day	5% 8% 4 10% 12% 9% 11% 8% 7% 7% 20%	2199
	21st to end	Day	6% 10% 5% 12% 9% 4 5% 6% 5% 7% 31%	2771
February	1st to 10th	Day	7% 10% 5% 12% 9% 5% 7% 8% 8% 8% 21%	1512
	11th to 20th	Day	7% 12% 4 10% 11% 4 7% 8% 6% 6% 25%	1575
	21st to end	Day	6% 9% 5% 13% 10% 5% 8% 7% 6% 7% 25%	1403
March	1st to 10th	Day	9% 13% 6% 11% 10% 6% 8% 6% 5% 7% 19%	1800
	11th to 20th	Day	8% 12% 5% 10% 6% 4 4 5% 5% 9% 32%	1910
	21st to end	Day	11% 10% 4 9% 7% 4 5% 6% 5% 7% 31%	2322
April	1st to 10th	Day	8% 9% 5% 7% 6% 4 6% 5% 7% 7% 35%	2160
	11th to 20th	Day	13% 11% 5% 8% 7% 2 4 6% 6% 7% 30%	2180
	21st to end	Day	13% 10% 3 8% 5% 4 5% 5% 6% 7% 34%	2520
May	1st to 10th	Day	12% 7% 3 6% 5% 3 6% 6% 7% 8% 38%	2520
	11th to 20th	Day	9% 5% 2 6% 6% 3 5% 5% 7% 9% 43%	2478
	21st to end	Day	18% 6% 3 6% 5% 3 4 5% 6% 8% 36%	2892
June	1st to 10th	Day	14% 6% 3 6% 6% 3 5% 5% 7% 8% 36%	2880
	11th to 20th	Day	23% 7% 3 6% 5% 4 5% 5% 6% 8% 29%	2880
	21st to end	Day	11% 4 2 5% 6% 4 6% 5% 7% 9% 40%	2880
July	1st to 10th	Day	7% 5% 2 4 5% 3 5% 5% 7% 10% 47%	2856
	11th to 20th	Day	11% 5% 2 4 5% 3 6% 5% 7% 8% 45%	2700
	21st to end	Day	7% 4 2 4 5% 4 4 4 7% 9% 51%	2791
August	1st to 10th	Day	8% 4 2 4 6% 4 5% 6% 7% 8% 47%	2507
	11th to 20th	Day	10% 5% 2 5% 5% 3 5% 5% 6% 8% 46%	2477
	21st to end	Day	12% 5% 2 5% 5% 3 4 4 5% 7% 48%	2471
September	1st to 10th	Day	11% 5% 2 4 4 2 4 5% 6% 9% 47%	2160
	11th to 20th	Day	14% 6% 2 6% 6% 3 4 5% 5% 7% 43%	2160
	21st to end	Day	10% 6% 2 4 3 2 5% 4 5% 7% 51%	1931
October	1st to 10th	Day	14% 11% 3 5% 5% 3 4 4 4 7% 41%	1800
	11th to 20th	Day	11% 9% 3 6% 5% 3 5% 5% 5% 8% 38%	1734
	21st to end	Day	10% 10% 5% 9% 6% 4 6% 6% 6% 8% 32%	1782
November	1st to 10th	Day	18% 13% 5% 8% 6% 4 3 5% 4 6% 27%	1493
	11th to 20th	Day	7% 14% 6% 13% 9% 5% 7% 5% 5% 6% 25%	1520
	21st to end	Day	8% 12% 7% 10% 9% 5% 7% 6% 4 5% 27%	1331
December	1st to 10th	Day	6% 12% 6% 12% 11% 6% 7% 7% 5% 7% 22%	1283
	11th to 20th	Day	8% 14% 6% 13% 8% 4 6% 7% 5% 7% 23%	1439
	21st to end	Day	4 7% 4 9% 7% 4 5% 5% 5% 8% 43%	2090
January	1st to 10th	Night	5% 12% 6% 13% 11% 5% 6% 5% 6% 9% 22%	4808
	11th to 20th	Night	4 7% 5% 13% 14% 8% 9% 6% 6% 7% 19%	4699
	21st to end	Night	6% 10% 5% 9% 9% 5% 6% 6% 6% 8% 30%	4893
February	1st to 10th	Night	8% 9% 4 10% 10% 5% 7% 6% 6% 9% 27%	2560
	11th to 20th	Night	5% 10% 5% 12% 8% 4 7% 6% 5% 7% 31%	2272
	21st to end	Night	4 6% 5% 9% 9% 5% 7% 6% 7% 9% 33%	1852
March	1st to 10th	Night	8% 10% 5% 9% 8% 5% 6% 5% 5% 8% 31%	2160
	11th to 20th	Night	6% 9% 5% 8% 7% 4 5% 6% 6% 9% 35%	2047
	21st to end	Night	9% 10% 4 7% 7% 4 6% 5% 6% 8% 34%	2033
April	1st to 10th	Night	7% 7% 4 7% 5% 3 4 6% 6% 8% 43%	1800
	11th to 20th	Night	12% 11% 4 9% 6% 3 5% 5% 5% 7% 34%	1728
	21st to end	Night	14% 9% 4 7% 6% 3 5% 6% 6% 7% 33%	1440
May	1st to 10th	Night	12% 6% 3 5% 5% 3 5% 6% 6% 6% 42%	1440
	11th to 20th	Night	12% 6% 2 6% 6% 2 4 4 5% 8% 45%	1418
	21st to end	Night	15% 5% 2 5% 6% 4 4 5% 6% 8% 38%	1378
June	1st to 10th	Night	11% 4 3 6% 4 2 4 5% 5% 10% 45%	1080
	11th to 20th	Night	19% 6% 4 5% 5% 3 5% 6% 5% 7% 35%	1080
	21st to end	Night	9% 5% 2 4 6% 3 4 5% 7% 10% 44%	1080
July	1st to 10th	Night	6% 3 1 3 4 3 5% 6% 8% 9% 52%	1101
	11th to 20th	Night	7% 4 2 5% 5% 3 4 5% 5% 8% 53%	1260
	21st to end	Night	4 3 1 3 4 2 3 5% 5% 8% 61%	1524
August	1st to 10th	Night	5% 3 1 3 3 3 5% 6% 5% 9% 58%	1432
	11th to 20th	Night	7% 3 1 3 3 3 4 6% 7% 8% 54%	1424
	21st to end	Night	11% 4 2 4 4 3 4 4 6% 8% 51%	1883
September	1st to 10th	Night	11% 5% 1 4 5% 3 5% 5% 6% 9% 48%	1800
	11th to 20th	Night	12% 6% 2 5% 5% 3 4 4 5% 7% 47%	1800
	21st to end	Night	10% 5% 2 4 3 3 3 5% 6% 7% 52%	2028
October	1st to 10th	Night	14% 8% 2 4 5% 2 4 5% 6% 8% 40%	2160
	11th to 20th	Night	8% 7% 3 7% 5% 3 4 4 5% 7% 47%	2207
	21st to end	Night	9% 11% 5% 8% 6% 4 5% 5% 5% 7% 34%	2574
November	1st to 10th	Night	17% 12% 5% 8% 6% 4 4 4 5% 6% 28%	2580
	11th to 20th	Night	7% 12% 7% 11% 10% 4 6% 6% 5% 5% 27%	2660
	21st to end	Night	8% 12% 6% 10% 8% 4 4 5% 5% 8% 29%	2846
December	1st to 10th	Night	6% 11% 5% 10% 10% 6% 6% 6% 6% 7% 27%	2892
	11th to 20th	Night	8% 13% 6% 11% 9% 5% 7% 6% 6% 7% 22%	3753
	21st to end	Night	4 7% 3 6% 6% 4 5% 5% 5% 5% 49%	5566

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	62% 8% 12% 11% 7%	2133
	11th to 20th	Day	61% 6% 15% 13% 5%	2220
	21st to end	Day	52% 7% 15% 19% 6%	2771
February	1st to 10th	Day	56% 8% 14% 14% 7%	1512
	11th to 20th	Day	57% 7% 11% 17% 7% 1	1584
	21st to end	Day	57% 7% 11% 17% 9%	1403
March	1st to 10th	Day	64% 8% 11% 13% 4	1800
	11th to 20th	Day	50% 9% 14% 20% 8%	1911
	21st to end	Day	51% 7% 17% 18% 7%	2322
April	1st to 10th	Day	44% 7% 15% 22% 10%	2160
	11th to 20th	Day	52% 8% 13% 18% 8% 2	2180
	21st to end	Day	48% 6% 15% 22% 8% 1	2520
May	1st to 10th	Day	41% 6% 13% 26% 12% 1	2520
	11th to 20th	Day	36% 8% 14% 26% 14% 2	2482
	21st to end	Day	47% 7% 14% 20% 11% 1	2892
June	1st to 10th	Day	44% 8% 15% 23% 10% 1	2880
	11th to 20th	Day	53% 8% 12% 19% 7%	2880
	21st to end	Day	39% 10% 18% 25% 8%	2880
July	1st to 10th	Day	29% 9% 24% 29% 9%	2778
	11th to 20th	Day	35% 8% 21% 25% 9%	2619
	21st to end	Day	28% 9% 22% 32% 8% 1	2636
August	1st to 10th	Day	32% 10% 22% 26% 10%	2491
	11th to 20th	Day	35% 7% 23% 27% 7% 1	2477
	21st to end	Day	34% 7% 15% 34% 10%	2471
September	1st to 10th	Day	33% 7% 19% 28% 11% 1	2160
	11th to 20th	Day	40% 6% 17% 27% 10% 1	2160
	21st to end	Day	31% 6% 17% 32% 13% 1	1931
October	1st to 10th	Day	44% 6% 17% 26% 8%	1800
	11th to 20th	Day	44% 6% 13% 27% 9% 1	1734
	21st to end	Day	50% 7% 18% 20% 5%	1782
November	1st to 10th	Day	60% 5% 14% 15% 6%	1493
	11th to 20th	Day	61% 7% 14% 13% 5%	1520
	21st to end	Day	60% 6% 14% 16% 4	1331
December	1st to 10th	Day	60% 7% 14% 11% 7% 1	1283
	11th to 20th	Day	60% 7% 17% 10% 5%	1440
	21st to end	Day	40% 6% 13% 19% 16% 6%	2090
January	1st to 10th	Night	58% 7% 15% 16% 3	4808
	11th to 20th	Night	62% 6% 15% 14% 3	4740
	21st to end	Night	51% 8% 16% 19% 6%	4893
February	1st to 10th	Night	54% 6% 13% 19% 8%	2560
	11th to 20th	Night	51% 6% 13% 20% 10% 1	2273
	21st to end	Night	45% 7% 14% 24% 10%	1852
March	1st to 10th	Night	51% 7% 15% 20% 7%	2160
	11th to 20th	Night	43% 8% 17% 22% 9% 1	2047
	21st to end	Night	46% 8% 16% 20% 9%	2033
April	1st to 10th	Night	36% 7% 16% 25% 15% 1	1800
	11th to 20th	Night	49% 6% 12% 18% 12% 3	1728
	21st to end	Night	49% 6% 13% 20% 12% 1	1440
May	1st to 10th	Night	40% 6% 11% 26% 16% 2	1440
	11th to 20th	Night	37% 6% 13% 23% 19% 2	1418
	21st to end	Night	42% 7% 14% 22% 15% 1	1378
June	1st to 10th	Night	34% 6% 15% 29% 13% 2	1080
	11th to 20th	Night	46% 7% 15% 19% 11% 1	1080
	21st to end	Night	34% 7% 21% 28% 9% 1	1080
July	1st to 10th	Night	23% 10% 23% 33% 10%	1070
	11th to 20th	Night	30% 7% 21% 33% 10%	1218
	21st to end	Night	21% 6% 19% 40% 12% 2	1439
August	1st to 10th	Night	23% 8% 23% 33% 12%	1424
	11th to 20th	Night	25% 8% 21% 33% 12% 1	1424
	21st to end	Night	30% 5% 16% 35% 14% 1	1883
September	1st to 10th	Night	32% 7% 15% 28% 16% 2	1800
	11th to 20th	Night	37% 6% 15% 29% 13% 1	1800
	21st to end	Night	31% 5% 14% 31% 16% 2	2028
October	1st to 10th	Night	41% 6% 18% 25% 9%	2160
	11th to 20th	Night	38% 6% 16% 28% 12% 1	2207
	21st to end	Night	48% 7% 15% 22% 7% 1	2574
November	1st to 10th	Night	56% 6% 15% 16% 6% 1	2580
	11th to 20th	Night	58% 7% 16% 14% 4	2660
	21st to end	Night	54% 7% 17% 18% 5%	2846
December	1st to 10th	Night	56% 6% 15% 17% 5% 1	2892
	11th to 20th	Night	60% 7% 15% 13% 5%	3751
	21st to end	Night	36% 6% 12% 25% 16% 4	5566

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	13% 7% 33% 25% 17% 6%	180
	11th to 20th	Day	13% 9% 29% 30% 17% 2	180
	21st to end	Day	12% 9% 32% 31% 15% 1	292
February	1st to 10th	Day	12% 10% 35% 29% 12% 2	252
	11th to 20th	Day	13% 5% 30% 35% 13% 3	240
	21st to end	Day	7% 5% 29% 43% 14% 3	198
March	1st to 10th	Day	14% 7% 35% 30% 13% 2	240
	11th to 20th	Day	10% 10% 35% 30% 13% 3	351
	21st to end	Day	16% 9% 33% 26% 13% 2	462
April	1st to 10th	Day	12% 12% 36% 27% 9% 4	420
	11th to 20th	Day	17% 13% 29% 26% 12% 3	431
	21st to end	Day	15% 10% 28% 31% 15% 1	600
May	1st to 10th	Day	13% 7% 25% 33% 18% 4	603
	11th to 20th	Day	11% 8% 25% 32% 17% 6%	625
	21st to end	Day	15% 11% 21% 30% 18% 6%	679
June	1st to 10th	Day	12% 13% 29% 26% 16% 5%	630
	11th to 20th	Day	23% 10% 24% 26% 14% 3	630
	21st to end	Day	11% 8% 23% 30% 22% 7%	630
July	1st to 10th	Day	10% 5% 24% 33% 22% 7%	621
	11th to 20th	Day	9% 8% 27% 29% 20% 7%	618
	21st to end	Day	7% 6% 24% 33% 20% 11%	684
August	1st to 10th	Day	9% 5% 21% 33% 23% 9%	626
	11th to 20th	Day	11% 5% 19% 35% 23% 6%	615
	21st to end	Day	13% 7% 23% 32% 20% 6%	495
September	1st to 10th	Day	12% 10% 32% 28% 14% 3	450
	11th to 20th	Day	16% 9% 26% 31% 15% 2	450
	21st to end	Day	16% 8% 29% 32% 13% 2	284
October	1st to 10th	Day	18% 7% 28% 22% 21% 4	270
	11th to 20th	Day	14% 11% 33% 25% 14% 3	270
	21st to end	Day	13% 12% 35% 26% 13% 2	297
November	1st to 10th	Day	24% 8% 29% 26% 11% 3	270
	11th to 20th	Day	13% 10% 40% 27% 9% 1	270
	21st to end	Day	11% 8% 38% 31% 8% 3	270
December	1st to 10th	Day	7% 7% 33% 36% 14% 4	248
	11th to 20th	Day	9% 12% 46% 26% 7%	180
	21st to end	Day	9% 3 36% 30% 18% 4	198
January	1st to 10th	Night	10% 8% 35% 34% 12% 1	950
	11th to 20th	Night	11% 9% 35% 34% 10% 1	950
	21st to end	Night	12% 9% 38% 31% 10%	1045
February	1st to 10th	Night	11% 7% 32% 34% 15% 2	900
	11th to 20th	Night	10% 7% 31% 38% 12% 2	704
	21st to end	Night	5% 5% 25% 40% 21% 4	592
March	1st to 10th	Night	11% 6% 31% 37% 14% 1	720
	11th to 20th	Night	10% 8% 33% 37% 12% 1	720
	21st to end	Night	15% 7% 27% 36% 14% 2	647
April	1st to 10th	Night	10% 7% 31% 37% 14% 1	540
	11th to 20th	Night	16% 7% 31% 36% 10% 1	533
	21st to end	Night	18% 9% 28% 36% 9%	540
May	1st to 10th	Night	14% 6% 27% 37% 15% 1	540
	11th to 20th	Night	13% 7% 29% 32% 18% 1	531
	21st to end	Night	16% 8% 22% 34% 16% 3	517
June	1st to 10th	Night	11% 6% 28% 36% 17% 2	360
	11th to 20th	Night	20% 5% 26% 31% 16% 1	360
	21st to end	Night	12% 4 21% 42% 20% 1	360
July	1st to 10th	Night	6% 4 20% 45% 23% 1	350
	11th to 20th	Night	11% 4 26% 38% 21% 1	348
	21st to end	Night	5% 4 23% 42% 22% 3	539
August	1st to 10th	Night	8% 4 20% 42% 24% 3	537
	11th to 20th	Night	9% 4 18% 40% 28% 2	534
	21st to end	Night	13% 4 24% 40% 19% 1	594
September	1st to 10th	Night	12% 4 27% 36% 19% 1	540
	11th to 20th	Night	14% 4 24% 39% 16% 1	540
	21st to end	Night	12% 8% 30% 37% 12% 1	602
October	1st to 10th	Night	20% 5% 25% 34% 15% 2	720
	11th to 20th	Night	12% 7% 29% 38% 11% 2	767
	21st to end	Night	15% 9% 31% 35% 9% 1	990
November	1st to 10th	Night	24% 7% 30% 32% 7% 1	925
	11th to 20th	Night	12% 9% 35% 32% 9% 2	950
	21st to end	Night	12% 10% 38% 31% 8% 1	950
December	1st to 10th	Night	10% 6% 34% 33% 13% 3	950
	11th to 20th	Night	12% 11% 32% 34% 10% 1	950
	21st to end	Night	11% 6% 31% 35% 14% 3	1045

Page generated at 2024-02-02 04:20:31. Version ac07

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